I hope it's pretty clear from my question title itself. I want to override autocomplete provided by module such as privatemessage to not suggest the current user(self) who is trying to send message. I tried doing some research about it but all I got was about overriding JS file.
I have used automcomplete with my custom form long ago & when I prepared the JSON, I removed current user from the list. But what to do if I have to do the same for some contributed module ?