ColorOS offers account management in the settings of the Oppo smartphone, where you can add, manage and remove accounts.

If an account is removed, the associated data is also deleted from the device, but not in a possible cloud.

Android 10 | ColorOS 7.0
Step 1:  Open the  Settings
Step 2:  Tap on  Users & accounts
Step 3:  Choose desired  Account
Step 4:  Tap on  Account  you want
Step 5:  Open the  Menu
Step 6:  Tap on  Remove account
Step 7:  Confirm with  Remove account
  1. Open the Settings
  2. Tap on Users & accounts
  3. Choose desired Account
  4. Tap on Account you want
  5. Open the Menu
  6. Tap on Remove account
  7. Confirm with Remove account

Oppo Instructions