Any way to make Communists disappear?

[GAGA Extrem]

Got to: Victoria 2\events\IdeologyEnabling.txt and delete lines 71-130. This will prevent the communist ideology from ever being activated.
Will not deactivate it if it already has been activated, though, so you will have to start a new game.

Alternatively you can mod their spawn chance to zero by changing line 499 in rebel_types.txt from:
"factor = 1.02"
to:
"factor = 0"

However, if you remove the communists chances are that they will just spawn another rebel faction. So your problem lies more in angry pops then communist agiators.
Have you issued all reforms that are desired? Have you checked that your pops can fulfill their needs? Check your pops and their militancy tooltip to see what drives them mad.

Rebel algorithm for communist rebels (from rebel_types.txt):

communist_rebels = {
	icon = 3
	
	area = nation 					# Stays within the nation
	break_alliance_on_win = yes
	
	# <this is the governement in the country> = <this is what the rebels want>
	government = {
		proletarian_dictatorship = proletarian_dictatorship
		presidential_dictatorship = proletarian_dictatorship
		bourgeois_dictatorship = proletarian_dictatorship
		fascist_dictatorship = proletarian_dictatorship
		absolute_monarchy = proletarian_dictatorship
		prussian_constitutionalism = proletarian_dictatorship
		hms_government = proletarian_dictatorship
		democracy = proletarian_dictatorship
	}
	
	
	defection = ideology				# Will defect to countries with proletarian dictatorships
	independence = none				# Does not strive for independence
	defect_delay = 18
	
	ideology = communist
	
	allow_all_cultures = yes
	allow_all_religions = yes
	allow_all_ideologies = yes
	
	resilient = yes					# Disbands on retreat
	reinforcing = yes				# Does not receive reinforcements
	general = yes					# Does use generals
	smart = yes						# Does not assault forts, tactically withdraw from battle, etc.
	unit_transfer = no				# Units do not remain after enforcing demands.
	
	occupation_mult = 1.0			# The amount of strength this rebel gains from taking provinces	

	# triggers a general rising, modifier will be multiplied with the countrys army strength and compared to the factions strenght
	will_rise = 
	{
		factor = 0.5
		
		modifier = {
			war = yes
			factor = 0.8
		}
		
		modifier = {
			factor = 0
			NOT = {
				is_ideology_enabled = communist
			}
		}
		
		modifier = {
			factor = 0
				 political_movement = yes
		}
		
		modifier = {
			war_exhaustion = 4
			factor = 0.95
		}
		
		modifier = {
			war_exhaustion = 6
			factor = 0.95
		}
		
		modifier = {
			war_exhaustion = 8
			factor = 0.95
		}
		
		modifier = {
			factor = 0.95
			any_neighbor_country = {
				government = proletarian_dictatorship
			}
		}
	}
	
	# The rebel type with the highest modifier for this pop gets picked
	spawn_chance = {
		factor = 1.02
		
		modifier = {
			factor = 0
			country = { civilized = no }
		}
		modifier = {
			factor = 0
			NOT = {
				is_ideology_enabled = communist
			}
		}
		modifier = {
			factor = 0
			government = proletarian_dictatorship
		}
		modifier = {
			factor = 1.015
			NOT = { political_reform_want = 0.05 }
		}
		modifier = {
			factor = 1.15
			social_reform_want = 0.15 
			NOT = { political_reform_want = 0.15 
			}
		}
		modifier = {
			factor = 0.01
			NOT = {
				OR = {
					pop_majority_ideology = communist
					pop_majority_ideology = socialist
				}
			}
		}
		modifier = {
			factor = 1.3
			pop_majority_ideology = communist
		}
		modifier = {
			factor = 1.15
			pop_majority_ideology = socialist
		}
		modifier = {
			factor = 1.015
			country = { plurality = 10 }
		}
		modifier = {
			factor = 1.03
			country = {
				any_neighbor_country = {
					government = proletarian_dictatorship
				}
			}
		}
		modifier = {
			factor = 1.05
			country = {
				average_militancy = 6
			}
		}
		modifier = {
			factor = 1.05
			country = {
				average_consciousness = 6
			}
		}
	}
 
 	#This is checked for EACH province in the Area of Operations
	movement_evaluation = {
		factor = 1
		modifier = {
			factor = 0.1
			units_in_province = 1
		}
		modifier = {
			factor = 0.001
			controlled_by = REB
		}
		modifier = {
			factor = 1.5
			average_militancy = 4
		}
		modifier = {
			factor = 1.5
			average_militancy = 6
		}
		modifier = {
			factor = 1.5
			average_militancy = 8
		}
		modifier = {
			factor = 2.0
			is_capital = yes
		}
	}
	
 	# Province Scope
 	#siege_won_trigger = {
 	#}
	
	#siege_won_effect = {
	#}
	

	# Country scope
	demands_enforced_trigger = {
		capital_scope = {
			controlled_by = REB
			province_control_days = 30
		}
	}
	demands_enforced_effect = {
		political_reform = none_voting
		political_reform = party_appointed
		political_reform = no_meeting
		political_reform = state_press
		political_reform = state_controlled
		political_reform = underground_parties
		
		nationalize = yes
	}
}