You can submit and withdraw your own amendments. You can also do this on behalf of another MP if you have their permission.
You can submit an amendment for the committee stage of the bill even if you’re not a member of the public bill committee. But you would need a member of the committee to act on your behalf in the committee meeting to ‘move’ the amendment, so that it could be debated.
If you have authorised your staff with the Public Bill Office, they can submit and withdraw amendments on your behalf.