Note: I want to delete the changelist only not the client.
The answers in the following link doesn't work when the pending changelist is from an old workspace which is in an offline machine Perforce: How can I delete a changelist that p4v refuses to delete?
Tried the following command p4 -u <user> -c <client> -H <host> revert -k <file(s)>
But I'm not allowed to do as the workspace owner is different.
Best Answer
First get the USER and CLIENT:
With a 2015.1+ server at this point you can just do:
With an older server it's a few more steps.
First get the HOST so you can bypass the hostname check:
Now login, revert the files, and delete the change: