Can a father or mother revoke the rights of a child's grandparents if they...?

What kind of deprivation of the rights of the grandmother/grandfather are you asking about?

The fact that the grandparents took care of the child does not give them additional rights in relation to the latter.

According to Part 1 of Art. 151 of the Family Code of Ukraine, parents have an overriding right over other persons to the personal upbringing of a child.

At the same time, according to Part 2 of Art. 257 of the Family Code of Ukraine, parents or other persons with whom the child lives, have no right to prevent the grandmother, grandfather, great-grandmother, great-grandfather from exercising their rights regarding the upbringing of grandchildren, great-grandchildren.