You may need to either:
-Buy a more directional mic (dynamic mics “generally” have a better off axis edge rejection)
-Buy a “vocal booth screen” like this
https://djcity.com.au/product/se-ele...SABEgLtgvD_BwE
-Move the mic to a different room
-move the mic into a wardrobe/cupboard
If the mic is figure 8 polar response, you can point the null (side) at the noise to reduce (may not help in your case)
As karbo states, you won’t fix it by turning down the gain, once you EQ/compress/level mix, the noise will still be there.
Best of luck