And they say I have a thing for long sentences.
Anyway yes you can do it, it will be unique to each game (give or take the odd game using the same engine) and it is not going to be easy in most cases. Equally I do have to ask what is a level? For instance if I am ripping a megadrive Sonic title then do I have to include every bonus level and bonus level type? After all theoretically any could be accessed from any "main" level, maybe less if you include levels where you technically should not have had enough chaos emeralds to get to a given level but hey. Going further what is a level in Skyrim, a level in GTA and a level in a modern flight simulator?
You have two options
1) ROM/iso ripping. Here if you delete level files from the game then it should work fine for those levels. This has been done a few times, however it was probably the first Sonic on the DS that had the last notable one here unless I missed something on the Wii (quite possible). Everything else tends not to have this as people tend to want 1:1 copies of games to be released.
2) Conventional ROM hacking. This can be straight up ROM hacking in the conventional sense, if a game has a level editor or something though you could probably do something with that. If you say put a warp outside each town in pokemon that sent you back to the pokecenter or something then you could restrict it to one "level".
Likewise what do you intend to do with this? If you want it for some gameplay reasons (you want to limit yourself, make your own demo, make a challenge run....) then fine, however level data has not been the bulk of game data for many years, if ever really, and you are not going to save much space by doing this.