If you want to return something that you have put together, do you have to disassemble it?

Not required to disassemble.

I bought a selve with 2 brackets, only open plasctic bracket and want to return but lost the receipt, can I return without receipt or with credit card record

No

Nope just bring the receipt

Nope, but you need the receipt

No, they do not expect you to disassemble.

Not at all. Just bring the receipt.

No not required. But original bill is required