How to remove files from changelist in perforce without losing modifications

Both of these operations restore a set of files to a previous state and are essentially faster, safer ways of undoing mistakes than using the p4 obliterate command (and you don't need admin access to use them).

In the case of "Rollback...", this could be any number of files, even an entire depot. You can tell it to rollback to a specific revision, changelist, or label. The files are restored to the state they were in at the time of creation of that revision, changelist, or label.

In the case of "Back Out Submitted Changelist #####", the restore operation is restricted to the files that were submitted in changelist #####. Those files are restored to the state they were in before you submitted that changelist, provided no changes have been made to those files since. If subsequent changes have been made to any of those files, Perforce will tell you that those files are now out of date. You will have to sync to the head revision and then resolve the differences. This way you don't inadvertently clobber any changes that you actually want to keep.

Both operations work by essentially submitting old revisions as new revisions. When you perform a "Rollback...", you are restoring the files to the state they were in at a specific point in time, regardless of what has happened to them since. When you perform a "Back out...", you are attempting to undo the changes you made at a specific point in time, while maintaining the changes that have occurred since.

Perforce keeps track of the files that it thinks that you have on your local workstation. If you delete those files locally (and don't "tell" perforce about it), then Perforce will still think that you have those files. If you want to get them back, you need to "force sync" the files. In p4v, you can use the "Get Revision..." item and in the subsequent dialog, you can check the "force operation" checkbox to tell Perforce to give you all the files again regardless of whether Perforce thinks that you need them.

Just to complete the information, if you ever do want to remove the files locally, you can do so through p4v by choosing the "Remove from Workspace" item. Doing so will remove the files locally as well as tell perforce that you no longer have those files so that next time you sync, those files will be retrieved from the server.