Can I use my Dell laptop as trade-in for a MacBook Pro?

No. Apple trade in only accepts their own devices, and when you try to get an estimate for other computer brands, you’re instructed to recycle it instead.

An independent reseller might offer a trade-in discount, so you can check Apple-authorized resellers in your area and see if any have such a program. As Zedairder said, Apple will not give you any discount as a trade-in of a non-Apple device.

Regards.