Select Categories → Income Categories in the left vertical menu.
If the menu is not visible, click the menu icon in the top-left corner.
In the mobile app, tap the menu icon in the top-left corner, then select Income Categories.
Click the income category group you want to delete, then select Delete Category Group from the popup menu.
An income category group can be deleted only if it doesn’t contain any income categories. If the group contains income categories, a warning message will appear and the group won’t be deleted.
If the income category group is empty, it will be deleted immediately, without a confirmation dialog.