Open up your Zoom application and select the drop-down arrow next to your user name. From here you can select "Log Out"
Then "Login" using your desired account via Google, Facebook, SSO or the e-mail you used when you signed up with Zoom.
If you are logged in with "Multiple Google Accounts" in your web browser, Zoom will automatically detect and choose your default Google account. The example below shows two accounts logged into Google, but only one is the default account.
Note: You can also switch between accounts much quicker if you are already logged in with multiple Google accounts.
For more information on logging in with multiple accounts please see: https://support.google.com/accounts/answer/1721977?hl=en