Is there any way to delete a tab? I made a horrible one a couple of months ago and I really want to get rid of it.
I don't believe so as once it is accepted and posted it is out there forever..... But you can make corrections to it.....
If I were you (and I never tried this but it may work) go in and when you update the tab just remove everything and say it was done because you know the tab was not up to par.....and then submit that and see if it is posted that way....

So what you would do is this:
1. Go into the tab and click on update
2. Remove the entire tab
3. Then place only the following:
Tab has been removed by the person creating the tab because I felt that it was not correct at all.
4. Submit only this... And see if it is accepted a few days later....
5. If it is then you have nothing to worry about.
6. If not, then I can only suggest you re-do the tab and make corrections to it and in the beginning of the tab just state what you did here about knowing it really isn't that good and you know it but that it can not be removed.... This way it is no reflection upon you..

I myself have done some tabs early in my guitar playing days ... And now look back on them and laugh..but if I feel like it I redo the entire song and make the correction and note when I did that in case someone gave it a low rating in the past ...so that others know that the tab has been corrected and is a lot better now.... Hope this all helps...
It says that after you go to contributions on your profile and click on your tab. How did you get something terrible up? I never get a good one up.
Yes Don is right. They don't let you delete tabs once it's approved.
The update is the blue "u!" to the right of your tab, it should be next to the date on this page http://my.ultimate-guitar.com/main.php?mode=contributions&showtab=2

Personally, I wouldn't try to remove the content unless it's a really bad tab and would get 1 star ratings. People might appreciate some of it or find it useful in some way. I'd rather re-tab, but it's not always something you wanna do - I mean you do get sick of listening to a song eventually.