If you hit Delete, the asset is fully deleted from the database. The only way to get it back would be to restore a database backup. Lansweeper 5.3 does not log who deleted assets or when, but the Lansweeper 6.0 beta does, in a newly created table called tblConfigLog. (To actually restore a deleted asset you would still need a database backup though.)
If you haven't already, contact support@lansweeper.com and include "beta" in the title of your message. We'll add you to our beta testers and send you the beta.