Well what i would recommend you is to look into the option of concurrent snapshot generation for your problem in reference to blocking.

This would really help u

Well you can specify that option provide you can rely on your backup strategy

You can as well try

sp_removedbreplication '<db name>'

this will remove all the entries corresponding to the replication. 

Also make sure you had followed the correct process for removing the database...

Configure SQL mail option and create an alert as per your requirement in the replication monitor and check the email option in the propertiers response tab.

It works try

Krish