WER stands for Windows Error Reporting (WER). Windows Error Reporting collects and offers to send post-error debug information
(a memory dump), using the Internet, to the developer of an application that crashes or stops responding on a user's desktop. No data is sent without the user's consent. When a dump (or other error signature information) reaches the Microsoft server, it is
analyzed and a solution is sent back to the user when one is available. Solutions are served using Windows Error Reporting Responses. Windows Error Reporting runs as a Windows service and can optionally be entirely disabled. If Windows Error Reporting itself
crashes, then an error reports that the original crashed process cannot be sent.
You can delete the files from
“C:\Users\username\AppData\Local\Microsoft\Windows\WER”.