The entry for a roll of 13 or 14 on the Wild Magic Surge table is:
You cast confusion centered on yourself. (PHB, emphasis mine)
Confusion is a 4th level concentration spell. The rules for concentration state that:
If a spell must be maintained with concentration, that fact appears in its Duration entry, and the spell specifies how long you can concentrate on it. You can end concentration at any time (no action required). (PHB)
The intent of the entry on the Wild Magic table seems to be for everyone nearby, including the caster, to be hit by confusion, essentially a less-bad version of casting Fireball centered on yourself. However, since the table doesn't specify anything special about concentrating on the spell, the caster needs to maintain concentration on it, and consequentially the spell should end if they stop concentrating on it.
RAW, is there any reason someone who rolls this result on the Wild Magic Surge table couldn't immediately drop concentration and end the spell?