Replication has been my favorite subject when it comes to resolving errors. I have found that many DBAs are stuck with the solving of the problem of replication for hours; however, the solution is very easy. One of the very common errors in replication occurs when replication is removed from any server. I have seen the following error as one attempts to remove replication from the same server when the publisher and distributor are on the same server.
Cannot drop server ‘repl_distributor’ because it is used as a Distributor in replication.
Cannot drop the distribution database ‘distribution’ because it is currently in use.
Try any of the following option. Either of them should work for you.
EXEC master.dbo.sp_serveroption @server=N'XXXX', @optname=N'dist', @optvalue=N'true'
EXEC sp_dropdistributor @no_checks = 1, @ignore_distributor = 1
Please do let me know your feedback regarding which one of the above options worked for you or if any of the other solution helped to resolve this issue.
Reference: Pinal Dave (https://blog.sqlauthority.com)