You should make it easier on yourself, generate a list of the non-vowels instead of trying to work on a string.
Stings in python are immutable so convert it to a list!
end_list = 
for item in list(text):
if item.lower() not in 'aeiou':
While you can simplify the above to,
return ''.join([item for item in list(text) if item.lower() not in 'aeoiu'])
Working on immutable objects is a pain so the first thing you want to do is always convert it into something useful, and then after working on it return it back in the same format you go it.
Everything I used in both sample functions is built-in and can easily be googled so if you don't understand something as and I will point you to the resources you need to get some understanding!
As always best of luck.