How can I return a couch?

IKEA has a return counter at their store. Get a number and wait your turn.

Bring the couch back at IKEA where you get it, you'll find counters says Return . . .

Returns & exchanges policy - IKEA. For a full refund, you can return your products within 365 days, even if you have assembled them, as long as they are in an unused and re-saleable condition. Please return them with proof of purchase and, if possible, the packaging. Returns & exchanges policy - IKEA