How to Reset Steam Game Settingsby Mark R. Frechione ; Updated September 22, 2017
Steam games such as “Team Fortress 2,” “Condition Zero” or “Portal” allow users to customize their settings to accommodate different player styles. Players wanting to return their game to its original settings can do so by renaming the source folder for that game. No longer able to access this folder, the game will create a new folder with default settings.
Exit the Steam application completely.
Find the Steam folder, usually located under “C:\Program Files\Steam\” on PC or “/Users/<user name>/Library/Application Support/Steam” on Mac.
Locate the particular game folder within the Steam folder. For instance on a PC, the file extension for a saved Portal game could look like, “C:\Program Files\Steam\SteamApps\<your account name>\portal.” On a Mac it would be, “/Users/<user name>/Library/Application Support/Steam/SteamApps/<your account name>/portal.”
Rename the game folder, for instance "\~portal" on PC or "/portal archived game settings" on Mac.
Start up Steam and open the game. The game, not able to find the original folder, will create a new folder with the default settings.