stems that are used to grow a new plant have wax on them to reduce water loss.
i dont see why you shouldn't be able to repot it. only go up one or two pot sizes.

welcome to GoY too.

oh, okay. great!
Wow. thank you for responding to me so fast. Appreciate it. and Thank you for welcoming me to GoY!

I think the 'wax caps' are used for aesthetic purposes but I don't think it's good for the plant at all. Such a strange idea to me, but I guess it helps to sell more plants. I would get rid of the wax altogether. Definitely treat your yucca to a larger pot as mentioned above, with fresh new growing medium. Get rid of all that wax as best you can so your plant can breathe better. Plants breathe via the roots and need fresh air. You can always top off with decorative stones or something that will not impede gas exchange.

Thank you Bathgate. This is also very helpful!

i assumed the wax was on the cut stem, that's they way we get them in the uk, not on the surface of the pot.

correct! It's on the stem. I should have clarified.

Leave the wax on it wont do any harm, it was put there to prevent the stem drying out when the cuttings were first made.