Follow the below steps to know how to add the Disable Customer Portal button on layout:
1. Click on the Accounts Tab
2. Select the record
3. Click on Edit Layout
4. Select the Buttons (Top left)
Add the Disable Customer Portal (Button)
5. Click on Save
Go back to the affected record, click on Manage External Account drop down and select Disable Customer Portal - Account
1. Go to Accounts Tab
2. Click on Merge Accounts
3. Search for the Account record
4. Select the record that needs to be Merge
Once the Account record is disabled as Customer Portal or Partner Portal then the Account can be Merged successfully.
Note: Please make sure to select the correct Account Record because once we disabled all the Community or Partner Users associated, will be deactivated.
See Also: Merging of accounts/contacts associated with the partner/customer portals