I am unable to change the master admin. Anyone know why?

Do you have any access as the Master Admin? 

I'd like to share some information, michael95.

If you are logged in as a Company Administrator, you'll want to reach out to your Master Administrator to transfer the role. Otherwise, follow these steps:

1. Go to the Gear icon > Manage Users.
2. In the Manage Users page, select the drop-down arrow next to the Edit link of the Company Admin you want to transfer the role to. 
3. Choose Make master admin.
4. Select Make master admin when prompted.

An invitation email will be sent to the user, and they will have to accept it to successfully transfer the role. I'm also sharing this article for more details: How to Transfer The Role of Master Administrator.

If you want to delete a user, you can open this article for reference: Add, delete, or change user access.

I'm just a post away if you need more help with QuickBooks Online user access. Stay safe.