Problem:
Is there a command line or other option for edge to allow you to restart in safe/clean mode and do not reopen the previous web site?
Resolution:
Microsoft Edge stores this temp. data in:
C:\Users\%username%\AppData\Local\Packages\Microsoft.MicrosoftEdge_8wekyb3d8bbwe\AC\MicrosoftEdge\User\Default\Recovery\Active
Delete all files and folders.
2nd option:
Open Command Prompt as Admin and type in the following:
start microsoft–edge:http://www.neilpatel.com and hit the Enter Key.
Hope this will help you to start microsoft edge in safe mode,
Write in comment box below ,your opinion if any other method you may know,