If you want to no longer be a part of the guild, you can simply choose not to interact with it, and live out your days in peace.
It may be expected to complete your duties, but it is in no way required;
If you simply want the security of not being able to be infected, you may do so.

However, if you for whatever reason want to remove the Garlic Injection from your blood, you will need an Acid Injection.
This gruesome injection is made with a Syringe. two Apples, a Slimeball, and a vial of Vampire Blood.
The Vampire Blood can be obtained by killing a Vampire with a Stake.


While not §ostrictly§r necessary, a Bucket of Milk will be very useful, since without it,
§4you will likely die§r after the injection.



Now, you must simply inject it (with Sneak + Use) and quickly drink the Bucket of Milk.
Then, your immunity against vampirism will have been destroyed.