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 you want to delete, then select Delete Category from the popup menu.
An income category can be deleted only if it isn’t used in any transactions. If the category is used, a warning message will appear and the category won’t be deleted.
If the income category isn’t used in any transactions, it will be deleted immediately, without a confirmation dialog.