You're probably fine. If you post a picture (I don't remember how much reputation one needs to post pictures, so apologies) but if the roots are healthy and they don't extend past 4-5 inches, it won't be an issue when it comes to transplanting them to a pot of soil. Tangled roots can become a problem if several plants are tangled together or are bunched up. A young tree can over come quite a lot, follow advice for a proper seedling care and you shouldn't expect problems.
You asked 'how do I undo this' - if you're trying to do something ornamental with the roots, I can't help. If you're trying to have a bit of fun growing an avocado, then you should keep going! Plant the seed with the top-of-the-egg side up (or if it's not shaped like that, the end where the root doesn't exit the pit) in soil a little further than trusted advice would suggest. This depends on the seed size, maybe 3-4 inches (7-10 cm) below the top of the soil and be patient!