Is it permissible to enter the bathroom with a paper on which there is a picture of a mosque minaret, and is it obligatory to search for this paper if it is forgotten and [to then] destroy it?

Minarets were not known during the time of the Prophet, peace and blessings be upon him; rather, they were innovated by Muslims due to the benefits they offer, such as serving as a visible marker for the mosque and for the elevation of the adhan (call to prayer).

Based on this, there is no prohibition against entering a bathroom with a paper containing a picture of a minaret, nor is there an obligation to search for it to burn or bury it.