User Help > Managing Source Files as Members > Making a Member’s Working File Writable
 
Making a Member’s Working File Writable
CLI EQUIVALENT 
si makewritable
If you want to edit a file locked by someone else, and you have no intention of checking the files back in, you can make the working file writable.
In the GUI, you can make your working file writable during the checkout process or from a Sandbox view.
Select a member or revision in the Sandbox view and select Member > Make Working File Writable.
In the Web interface, you can make your working file writable during the checkout process.