After you add your Synced and Manual accounts you may find that you have added an account you no longer want to see. In Monarch Money, you have the ability to add or remove accounts whenever you like.
After you select the account you want to remove, look for the edit icon. In mobile, this appears as a pencil icon. On web it is "Edit Account." Both are in the upper right of that page.
The "Delete" option is at the bottom left of the edit screen (to prevent accidental deletion). Simply click the gray delete button, and a popup will appear asking if you are sure. Click the red delete button and the account is removed!
By deleting account, you will be removing all its data and transactions from Monarch.
Be aware: if you remove and then reconnect an account, you will often lose historical data. Any rules and customizations should remain.