How do you get out of the dark brotherhood

You can leave the Dark Brotherhood by breaking one of the five tenets.

Tenet 1: Never dishonor the Night Mother. To do so is to invoke the Wrath of Sithis.

Tenet 2: Never betray the Dark Brotherhood or its secrets. To do so is to invoke the Wrath of Sithis.

Tenet 3: Never disobey or refuse to carry out an order from a Dark Brotherhood superior. To do so is to invoke the Wrath of Sithis.

Tenet 4: Never steal the possessions of a Dark Brother or Dark Sister. To do so is to invoke the Wrath of Sithis.

Tenet 5: Never kill a Dark Brother or Dark Sister. To do so is to invoke the Wrath of Sithis.

only tenet 4 and 5 are the ones that will get you kicked out.