You are free to do that and will not have to redo any of your work that you have done with the previous rabbi.
However, you may have to restart your payment, as your payments are how we are able to pay our rabbis.
We do provide a 30-day window where we will help you switch rabbis
with no extra cost. However, if you are outside this 30-day window, you
cannot get “credit” toward your new conversion rabbi with money you've paid in with another rabbi.