No, You can't just delete everything in the WinSxS folder.
Deleting files from the WinSxS folder or deleting the entire WinSxS folder may severely damage your system so that your PC might not boot and make it impossible to update.
You can, however, reduce the size of the WinSxS folder using tools built into Windows.
You could refer to the following official article as your reference:
You can use Disk Cleanup to reduce the number of unnecessary files on your drives, which can help your PC run faster. It can delete temporary files and system files, empty the Recycle Bin, and remove a variety of other items that you might no longer need.
Hope above information can help you.
If the Answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.