All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
As for ablution in the bathroom it is permissible and valid. But the person should not perform ablution in the bathroom if there is another person urinating in that place unless this person is his wife and her husband, or a small child since the child does not have an ‘Awrah.
Allah knows best.