Is it permissible to pray in a mosque from which a shrine that was located within it has been removed, so that the mosque is now completely separate from the shrine, with its own entrance and an independent wall, and the shrine is now used as a storage facility for the mosque, knowing that previous fatwas by Ibn Baz permit praying in a mosque next to which there is a separate grave, and can this be compared to the permissibility of children playing with statues and the humiliation of pictures and statues by using them for other purposes, as mentioned in the hadiths?

There is no objection to praying in a mosque next to which there is a grave, if there is a separating wall between them, or if each has a separate entrance. In this case, the prohibition against building mosques over graves does not apply. Indeed, the Prophet, peace and blessings be upon him, was buried in Aisha's chamber, and the wall of the chamber served as a separator between his grave and the mosque. Scholars have issued fatwas permitting prayer in mosques that are separated from graves by a wall, such as the mosque in Ta'if which contains the grave of Ibn Abbas, may Allah be pleased with them both. This was affirmed by Ibn Taymiyyah, Ibn Baz, and Ibn Uthaymeen, as the wall is considered a sufficient separator.