I'm not sure if you mean the whole floor or the bottom of the steps....
If the bottom of the steps, depending on how much you're talking about an sds and chisel set could do it. If it's deeper I'd work out a way to get a roughly even depth with an angle grinder/similar then chisel that out.
If the whole floor I reckon paying someone in one go is the way to go. You need to dispose of all the rubbish as well so I think even DIY costs will add up.
I'm not sure if you mean the whole floor or the bottom of the steps....
If the bottom of the steps, depending on how much you're talking about an sds and chisel set could do it. If it's deeper I'd work out a way to get a roughly even depth with an angle grinder/similar then chisel that out.
If the whole floor I reckon paying someone in one go is the way to go. You need to dispose of all the rubbish as well so I think even DIY costs will add up.