Is it permissible to use the restrooms on other floors in a commercial tower, knowing that they are clean and empty, and that water and electricity are available on all floors, and knowing that the company does not explicitly prohibit it?

If there is no condition specifying bathrooms for each floor, it is permissible to use any of them, as they are often available to all workers and visitors, and there is no difference as long as the water and electricity belong to the building.

However, if there is a condition specifying bathrooms for each floor, it must be adhered to, based on Allah's saying: ﴿O you who have believed, fulfill [all] contracts﴾ (Quran 5:1) and the Prophet's saying, "Muslims are bound by their stipulations."

This condition must be observed when there is no need. But if there is a legitimate need (such as someone who is late for prayer or finds waiting difficult), this benefit should be extended and not withheld from the one in need. There is a fear of sin for one who withholds it, or of their condition becoming void.