Unfortunately, if you mean by "delete" as to obliterate all presence in the realm of Wikitree, no, cannot obliterate. That leaves "recycle"
Once a person is profile forever after (unless the whole of WT crashes) that record's position, with or without (recycled) information remains ... that's why the format for it can be recycled
The format is distinct from the person -- the format is a template with a series of assertions ... the format itself occupies a "space" in the computer records ... when recycled it is given new assertions etc but the "space" occupied is unchanged
I don't think I'm explaining this very clearly, though -- you can search g2g for posts on "can I delete this profile", "deleting a profile" and other such terms involving "delete" and I suspect several hundreds of posts could be located