I think this post isn't about cheats, but about legal ways for do this thing.

I want know if there are some way for leave a guild/faction definitively, and how work these things.
Also i ask if someone has never taught at a mod with something for leave a guild/faction.

You can be expelled from a guild, generally this involves theft of guild property or killing another guild member. There isn't a mechanic for resigning however.

Never having anything to do with the guild again is no different from actually leaving apart from the fact that it's possible in-game. If you want to lose your standing (reputation etc) within the guild to make it look like you really left, Hungry Donner's info on getting expelled might help, I don't know. I've never felt the need to leave guilds, if I don't want anything to do with them any more for a character I just ignore them for the rest of the game.

At lower levels, factions can play a huge part on how you can act. The main downside being the unpredictable disposition changes that occur because of joining certain factions.

There's also the downside that you're stuck with the Great House you join no matter what; although you could argue that's actually a smart game mechanic, as freely leaving and joining different Great Houses would be a little messed up.

Removed while I figure out how to delete posts on here.

With game mechanics, yes. Also, unlike in real political parties, you cannot just change the House. You're one for life, or you get killed. It's that simple in the cruel world of Nirn. The Houses are basically at war, so changing between Houses isn't tolerated.

You should be able to resign from Guilds though, I think. It's bad to get some unwanted disposition with other parties by joining this-and-that, especially by accident if you're a new player.

...Also if you're expelled from the Blades, you're out. This can really complicate the MQ
If you are expelled from the Legion twice, you're out and try getting any help from a legionairre (including the armorer in Ebonheart) after that.

thank you of your help, but now its better that i explain my problem.

I have a Nord Battlemage and i have started a career in the Mages Guild: this mean that i will become in some way an enemy of House Telvanni, because the Mages Guild and House Telvanni hate each other.
You know well that Telvanni say that killing for gain a better rank is regular among them, and as Nord kill or be killed is the regular way of every Skyrim warrior, and as Battlemage i have any moral problem to kill someone for gain an upper rank, then Telvanni seem a very good House for me, but as roleplayer i can't join Telvanni, or, if i want become one of them i must leave the Guild before join them. After all if i belong to telvanni what i do in the Guild that opposite my House?

Now, i think: i must kill someone or doing some robbery for leave a Guild? There isn't another way for do the same thing avoiding the violence?

Ok, i'm not a saint, and my Battlemage hasn't great moral problem to do an action like this (i will do very easily, simply going to the hated Galbedir and dispatch her with some cold or poison touch spells) but i hope that someone will find a way to do the same thing avoiding illegal act-maybe a mod that solve this problem.

For now i'm thinking to become Redoran avoiding the Guild/House problem - ok, Redoran are Temple fanatics but they are warriors, and as Nord and Fighters Guild member i have much respect for other warriors, especially these from Redoran House: after all a Battlemage is partly a warrior and can stick with them well.

Outside of great houses it's possible to join any faction in spite of their apparent enmities. For instance you can join both Telvanni and the Mages Guild, or the Fighters Guild and the Thieves Guild, or the Temple and the Imperial Cult. Sometimes you have to juggle or even refuse some quests (such as Eydis's Sotilde's code book if you are a member of both the Thieves and the Fighters Guild) but it can be done.
Incidentally, there is a way to join another Great House and Hlaalu through a glitch but you will only be allowed one stronghold.