How to withdraw ones name from an already published paper
The most effective and natural method would be to simply ask, possibly explain your situation if needed, to the editor or publisher of the paper.

If you have more issues with the publication, you are free to mention them, but this is mostly orthogonal to whether you want your name on the possible publication.

It would also be a good idea to inform your co-authors of this decision, as they may take it badly if they aren't notified.