Merchants can be used on Expenses & Subscriptions. They help separate the data so you can see how much your expenses are for going out ETC...
The first step to create a merchant is to go to the Merchants on the Dashboard:
Now you will need to click on the merchant that you're wanting to edit.
Click on the Delete Merchant button under Actions Box.
Now you will have a pop up confirming you want to delete this merchant. Press the blue button to confirm.
You have now deleted the merchant.