I am new to clearcase so i would like to remove the baselined activities(i.e., already done activities) in my view any there any command is available to remove them or is it possible to remove them in Windows GUI.
The easiest way is to make those activities "invisibles", that is:
But that will work only if you are the owner (creator) of the activity you are locking obsolete.
(See activity states and
cleartool lock, the API command behind that GUI operation)
You can't remove an activity already included in a baseline. You will need to remove the baseline first, then remove the activity from the stream.