Handling Modified Without Checkout Files
If you are going to modify or delete a file under Perforce version control, the read-only status of such file should be removed. WebStorm takes care of automatically making files writable. However, you can change read-only status manually, which may happen in a number of ways; for example:
With the Clear Read-Only Status option enabled, you make a file writable using file system.
When a read-only file is opened in the editor, you double-click lock icon in the status bar.
You remove read-only attribute externally, using file properties.
In these cases, the file gets status Modified without checkout and appears in the Local Changes tab of the Version Control tool window.
To resolve 'modified without checkout' files
In the Local Changes tab of the Version Control tool window, expand Modified without Checkout node, and select the desired file.
On the context menu of the file, choose Check Out. The file becomes writable, and moves to the active changelist.