Select data Only if it doesnt have a certain value inside it

we have a legacy case management that runs via sql thru ms access.

our table example shows like this

TABLE

is there a way to pull or select show a certain data only if it doesnt have a certain SNUM.

like we have casenum with multiple snum entry. but we only want to select casenum that never had an entry from a certain snum

so if for example there is a casenum with an entry only from 151 and 152 but no entry from 153 and 154 then it will show.

but if a casenum has an entry from snum 153 or 154 then it will not show it