take it out then put it back? its not a difficult thing to do.

What watterson suggested is probably the best thing that you can do. Even if you have it disabled with prec_mode 0 (I think that's the command), you won't be able to play on any casual or matchmaking servers.

Either that or you can make binds to manually start and stop a demo with the in game demo system. The hardest part (for me personally) is actually remembering to hit the start bind since I was so used to PREC doing it for me

if you are really lazy you can make a .bat file that you double click to switch out your custom folder in order to add/remove prec
so you make one folder and name it custom_with_prec or something and then another named custom_without_prec
then in order to create the .bat file you just open a notepad and put this in and save as a .bat or windows batch file

rmdir "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom"
mklink /j "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom" "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom_with_prec"

and name it prec.bat
and then make another one with this instead and name it whatever you want (prec_off or something should be fine)

rmdir "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom"
mklink /j "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom" "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom_without_prec"

dr shadowpuppet told me he uses a similar symbolic link for replacing his custom folder in order to do tftv casts but figured out the logic to have just one .bat file that toggles it

if you want to get really fancy you can also make shortcuts to launch the game in different dxlevels (for example, if you normally play on dx8 with prec but need to use dx9 and without prec in order to play matchmaking)
all you have to do is make a new shortcut (right click -> new -> shortcut) and direct it to steam.exe
then open its properties (right click -> properties) and change the target from

"C:\Program Files (x86)\Steam\Steam.exe"

to

"C:\Program Files (x86)\Steam\Steam.exe" -applaunch 440 -console -novid -h 1080 -w 1920 -dxlevel 81 -full

adjust accordingly if you have steam installed on another drive or to change it to whichever launch options you want, the important part is that the directory for steam is in quotes and afterwards you have -applaunch 440 to launch tf2
iirc having -dxlevel in your launch options after the first time you change it makes it take forever to alt tab (at least for fullscreen) so to use this you would just put the .bat files and separate steam shortcuts (for the launch options you want to change) into one folder and then in order to play mm you just double click the bat file, then double click the steam shortcut and it will launch tf2, then close the game and relaunch it normally from within steam (you may not need to do this if you use windowed)

1. Launch TF2. Do _not_ launch casual or comp MM. Once those screens are launched and complain about prec, you have to restart TF2 to get past them.
   
2. Verify prec is loaded via "plugin_print" in console
   
3. If loaded, unload prec via "plugin_unload prec" or "plugin_unload 0" where the 0 is the index of prec from the plugin_print command output. Likely it's 0.
   
4. Verify prec is unloaded via plugin_print.
   
5. Now you can play casual or comp MM. They won't complain about you having PREC loaded.
   
6. When you have scrims or a match or something, you can load prec by "plugin_load addons/prec" from the main menu. Or you could just restart the game.

Or you could bind a key to "ds_record" and a key to "ds_stop" and just remember to press one key before your scrim/match and press the other after. ds_record will name the demo with a timestamp.

rmdir "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom"
mklink /j "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom" "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom_with_prec"

rmdir "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom"
mklink /j "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom" "C:\Program Files (x86)\Steam\SteamApps\common\Team Fortress 2\tf\custom_without_prec"

Nice! Just so I know, how does it work? Do I need to have everything in my custom folder in both folders(Minus p-rec)?