In TortoiseHG, you can disable the setting as follows:
Go to the "Synchronize" screen via the menu View -> Synchronize or by clicking this button in the toolbar:
Click the "Options" button under the list of commits:
In the options window, there's a checkbox for the "force push" setting:
By the way, when force is enabled, you should already see this below the "Options" button in step two: