You may have created an income or expense group a while ago, used it a few times, and now you don’t want to use it again. However you cant delete a group which has been used.
Now you can choose to Close that group instead. Closed groups will no longer be visible in the cashbook for the creation of new transactions or when importing transactions. However it will still be available for search or reporting on old transactions.
To close a group, go to the Functions/Setup/Chart of Accounts menu option, edit the group in question, and choose the Close option.