how do I verify a new number and delete a old number from my rover account?

Here is the problem, I have a old number on rover and need to get it deleted but it wont let me delete it because it shows as my primary number and trying to verifiy a new number for my rover account and need it to be my primary number on rover instead of the old number. My question is, Does someone know how to go about doing that or that can help me out in anyway with changing my old to new number on rover?