How do I delete my save files?

RenPy saves your data in it's own folder. Simply look for the one labeled Full Service and delete the contents. You may then start your game after.

According to RenPy documentation, you can find them in the following places:

Where does Ren'Py store my save games and persistent data?

The Ren'Py engine stores save games and persistent data under a separate folder. It's exact location depends on the host operating system.

Windows:

%APPDATA%/RenPy/game_directory

This is usually:

C:\Documents and Settings\YOURNAME\Application Data\RenPy\game_directory

Where YOURNAME is your username.

Mac OS X:

~/Library/RenPy/game_directory

Linux/Other:

~/.renpy/game_directory

In each case game_directory is the directory for the game in question.

Also, in case the game runs from a thumb-drive, and there exists a directory called "Ren'Py Data" in the root of said drive, Ren'Py will use that to store persistent data.

Special Handling For Steam

When playing on STEAM, it saves your games in it's own local folder as well as using the above folder. 

To access the local files:

1. Right-click Full Service
2. Click Properties
3. Open the tab called Local Files
4. Click Browse Local Files

In the local files, go to

...\Full Service\game\saves\

delete the .save files from there.

If you want to restart your progress entirely, go for deleting persistent as well.