What i would do if I were you.... is to go to "manage domains" in the panel, click the "edit" button for the domain you are wanting to restart. Then for the setting "Run this domain under the user:" change the dropdown to "create a new user" then click the "Change Settings" button at the end of that section.
That will cause a new user to be created on the server and the domain will run using that user. You will have a fresh empty user that you can use for your new one click install. Plus all your old files will still be available under your old user should you need anything that is there.