Please let me know how to delete a CVS tag which was already created from eclipse.
If the tag is removed, can a new tag be created with same name?
I don't think there's a way from Eclipse...you'll have to go to the command line and run:
cvs tag -d <tag> <file/directory>
or if the tagged files are no longer on your system:
cvs rtag -d <tag> <location_in_repository>