From Latin 'abolere' (to cause to die away) — the French '-ish' ending shared with 'demolish' and 'punish.'
To formally put an end to a system, practice, or institution.
From Middle French aboliss- (stem of abolir), from Latin abolēre (to destroy, to cause to die away), from ab- (away, off) + olēre (to grow), from PIE *h₂el- (to grow, to nourish). Roman legal language used abolēre specifically for rescinding laws and wiping out debts. The earliest English uses (1520s) were legalistic — abolishing statutes, not merely ending
The '-ish' ending in 'abolish' is not the English adjective suffix (as in 'foolish') but comes from the French inchoative verb stem '-iss-,' which indicated the beginning or progress of an action — making 'abolish' one of a distinctive family of English verbs borrowed from French that all end in '-ish.'