If I want to say you can stay there by yourself...eske mwen dwe di: ou met rete la pou kont ou? Ede'm tanpri :)

Yes, you are correct.  Ou byen di'l.
Haitian Creole word 'mèt' is all about giving permission or allowing someone to do something

You can stay here by yourself.
You may stay here by yourself.
Ou mèt rete la pou kont ou.

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words