Can i mention Allah swt in a bathroom that has a bathtub but no toilet?

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.

There is nothing wrong with mentioning the Name of Allah, The Exalted, in a bathroom that is used exclusively to perform Ghusl and ablution where people do not relieve themselves because it is not usually filthy, especially if the remembrance of Allah has a reason such as reciting the Basmalah before the ritual purification or praising Allah, The Exalted, after sneezing or returning the greeting of peace.

As for a place allocated for relieving oneself and answering the call of nature, most scholars hold that it is disliked to mention the Name of Allah, The Exalted, therein. Instead, one may mention the Name of Allah, The Exalted, inaudibly in his heart.

Ibn Qudamah said in Al-Mughni: “It is impermissible for a person to mention the Name of Allah, The Exalted, when relieving himself except (inaudibly) in his heart, and this was deemed disliked by Ibn Abbas, ‘Ata’, and ‘Ikrimah. Ibn Sireen and An-Nakh‘i are of the view that there is nothing wrong with it because the remembrance of Allah, The Exalted, is praiseworthy in all states.” [End of quote]

Allah knows best.