Can I trade my 15 inch MacBook Pro with Touch Bar for the smaller model?

If you purchased it directly from Apple within the last 14 days you can return it and then buy the 13" model. If you purchased somewhere else recently, check their return policy.

If you have had it longer, Apple has a trade program. See: Trade in with Apple GiveBack - Apple

JamieRowlex wrote:

I was wondering if It‘s Possible to trade a 15 inch MacBook pro For the 13 inch model

You probably come out better if you simply sell it on the open market and buy what you want.

If you bought from a Reseller, rather than direct from Apple, the Reseller's policies apply.

Returns Not available in HongKong or Singapore (even direct from Apple).

In those areas, you buy it (even direct from Apple) you own it. No returns.