I have a Weed eater riding mower 12.5 hp 32" cut. Model # 733848. After starting, it dies when I release the clutch pedal. I disconnected the seat switch, no change, it does the same thing.

Have you looked underneath to see if something is causing excessive load like long grass caught around the spindle

Hi,
Disconnecting the seat switch has not been allowed to defeat safety switches in a number of years. It is still most probably a faulty seat switch.
Peace,
Clarke

No high grass around the spindle. Not sure how the seat switch could be faulty if its disconnected

Hi,
Then suspect the bearings in the spindle, or perhaps the pivot in the engaegent arm of the idler which is sometimes common place to look on an AYP product.
Peace,
Clarke

Hi,
Just another thought, How do you think disconnecting does anything. Personally I never do such things even though I can figure out the entire schematics from my electrical engineering training?
Peace,
Clarke

Blade engage safety switch also might be sticking

Problem resolved.