An EditWar is what happens when several people start adding and then removing content. Usually this is an argument. EditWar's are bad for both the Wiki (it increases the size of pages and the clarity of the logs) and the users, since often content gets lost or mangled.
If you see something your want deleted, delete it only once. If it really needs to go, someone else will delete it as well. If you post something and it gets deleted, rememeber that this is HowWikiWorks, and you shouldn't be offended.
But... Don't go messing with someone's user page unless it's just routine stuff (fixing typos, fixing formatting, noting outdated statements). A UserPage is a special, private domain.