Please support my decision to annul my role as godfather.
Unfortunately, because I do not know any of the reasons why you wish to quit being a godfather, I cannot do that. All I can say is that when you accepted the position of godparent, you took on a solemn obligation to support the parents in raising the child to be a Christian (canon 872, Code of Canon Law). To abandon that obligation without just cause would be a serious matter indeed.
If your relationship with the child’s parents has deteriorated to the point that it would not be in the child’s best interests for you to be a regular part of their lives, you might suggest to the parents that they ask another Catholic whose spiritual maturity and orthodoxy they trust to act as a spiritual mentor for the child. Perhaps, in time, the child might choose this mentor to be his or her confirmation sponsor.
You should be aware, though, that such a mentor cannot “replace” you as a godparent because, as witnesses to the child’s baptism, godparents cannot be “replaced.” While such a solution might end up being in the best interests of the child, it is not an ideal solution. The ideal solution would be for you and the child’s parents to mend your relationship for the sake of the child.