Actually, much needs to be added to the question of the title to have a chance of responding with any rationality. There are several variables.
There are parents who are plainly evil, mean and abusive to their children. These may not deserve respect, but halacha does not give a blanket exemption from kibud av v’em.
There are also parents who have a poor relationship with a child, and it is often that the child is a factor in this dysfunction. That child may well feel that the parents are horrible specimens of humanity, but this could be exaggerated due to anger and whatever other emotional variables are present.
Sometimes a child wants to direct his/her life according to a style that is foreign and offensive to parents, who object and do not comply. One may question whether parents should try another approach to parenting, but the conclusion that parents deserve to be disrespected is inaccurate.
There is much to wonder about the details of the question. I would hope that commenters refrain from offering psak halacha, even if qualified to pasken, until there is more information.