How to completely get rid of replication subscriptions?
Take a look at this article: https://www.mssqltips.com/sqlservertip/2710/steps-to-clean-up-orphaned-replication-settings-in-sql-server/

Try dropping the old subscriptions, all publications and then removing replication from the DB, i.e. 

exec sp_dropsubscription --on all subscriptions


then

exec sp_droppublication --on all publications


then

exec sp_replicationdboption


Also, take a look at this question: How to fix a messed up replication on MS SQL Server