I am only one person working on project - so I am developer without PM above me. I finished portal, hovewer client from time to time attacks me with request such as "make font bigger" or change margin in css or make button which makes "xxx and yyy". There are simple task, sometimes only for few clicks, but it takes my time and I hate doing such tasks. On the other hand I understand those people, while sometimes small fix helps them a lot in work. What say them on communicators - it's hard to ignore them. Is disabling communicators best solution - but I need it to communicate with my co-workers. What you do in such situations?
Create an established queue where your users can submit requests, in a manner that doesn't disrupt your day-to-day workflow.
From the sounds of this you are getting requests via a communication channel that you check regularly, you might try to move it off to the side.
Cutting off communication is NEVER a good solution. Also, I would formalize a process and time schedule for when you get to those types of requests. I've found great success with this simple approach.