I know this is an old thread, but it's one of the first to come up in a search on this topic. The proposed solution above is not correct. That changes the Internet Explorer cache, not the Edge cache. As far as I know, Edge offers no way to move the cache location through the app itself, which is the primary reason I'm still using IE. I'm currently contemplating using mklink to redirect the folder to a Ramdisk.
For anyone who's interested in trying that approach, the directory where Edge stores its cache files is:
C:Users****AppDataLocalPackagesMicrosoft.MicrosoftEdge_8wekyb3d8bbweACMicrosoftEdgeCache
To execute the mklink command, you'd issue something like this at a command prompt run as administrator, obviously editing for your username and for your desired destination - my example is to a directory named EdgeCache on a volatile Ramdisk with driver letter R.
mklink /J "C:Users****AppDataLocalPackagesMicrosoft.MicrosoftEdge_8wekyb3d8bbweACMicrosoftEdgeCac he" "R:EdgeCache"
(EDIT: Not sure why the post is inserting a space in the word "cache" in that example, it's not there in edit mode. Be sure to remove it if you're doing a cut and paste.)
Full disclosure: I haven't tried this myself yet, but it should work. I'm just holding off trying to think of any way this could cause an issue. I presume mklink is still operative in safe mode, for example, but I am not 100% certain.