The folder is a hidden one and can only be deleted with the administrative permission. As, the folder “$Windows.~BT” stores the backup of the entire Windows files, so naturally, the size of the folder is significantly large.
And these files will be used to reclaim or restore any data if anything fails to be migrated properly to the newer one. When you upgrade (or try to upgrade) the current version of Windows to the latest one, the upgrade process automatically creates a back up copy of entire Windows directories including useful system files, all user’s profile etc. ‘$Windows.~BT’ Folder is a kind of hidden folder which is created at the time of up-gradation of your Windows version.
