The mod will be effectively deleted from your computer once you completely exit the game.Alternatively, you can click on 'View mod in workshop' (the button with the Steam icon) and unsubscribe from the Workshop itself. Hover over it, and click on 'Unsubscribe from mod' (the red X button).Go to the Mods menu from the main menu, and find the mod you wish to uninstall.
If you subscribed to a mod from the Steam Workshop, you can uninstall it from within the game: Instructions for uninstalling mods from the Steam Workshop: You might see a download progress bar in the list item if it takes a while to download. Return to the game, and you should see the mod listed in the Workshop mods list. Browse items in the workshop, and when you see a mod that you like, click on the 'Subscribe' button.
Instructions for installing mods through the Steam Workshop:
