Perforce has great tech notes and one of them is Perforce Reverting Submitted Changelists.

Here is how one rolls back to version N-1 .

> p4 sync …@N-1

> p4 add deleted_file
> p4 edit foo bar baz

> p4 sync …@N

> p4 resolve -ay

> p4 sync …

> p4 resolve

> p4 delete added_file

> p4 submit …

You can also do a simple rollback of a file like in this example.

> p4 sync foo#7

> p4 edit foo

> p4 sync …

> p4 resolve -ay

> p4 submit …