Summary
You cannot delete an account in EngageIP. The correct method is to archive the account. See below for Instructions.
Archiving Process
Set the account status to 'Cancelled' or the appropriate deactivated status
During the cancel process, select whether to prorate existing services or not
Optional: Using the tools tab, rename the account by appending 'REMOVED-' to the account name. Or use any other naming convention so that it's obvious in reports or when searching (apart from using the status to indicate) that the account is considered archived
Optional: Using the tools tab, change the account to an Owner you created called 'Archive'
Note: Step #3 above involves creating an owner for the purpose of archiving accounts. You can create it as unbranded to simplify things, and so that you aren't taking up a branded license (if you have a set limit)