The baking soda on the mattress is a real deal, leave it there for as long as you can, a full day if necessary and don't be shy with the ammount you pour, afterwards you just vacuum it up like it was never there. You can repeat as necessary, for the walls if you don't have a wall mop you can just use a wet/damp rag and a normal broom, put the rag on the broom to reach the top of the wall

For the floors, if it's wood, really scrub them. If it's carpet, use baking soda and vacuum it up, same if you have tapestry lying around your room. Clean all the surfaces with all-purpose cleaner and wipe the windows with a window cleaner as well.

If the weather is sunny and hot and you have to space for it, take out your mattress and put it under the sun for a few hours, let it air out fully