This is a very easy achievement. When you are in career mode, scroll down and click on Transactions. When you click on it, you should have more options on your screen, scroll down and click on trades. You can trade with any team and you can trade for any player. It is easiest to make a new career or use a career that you are not trying to win anything and trade for a really bad player. Or once you make the trade you can quit without saving. Try to trade for a player that is bad overall and trade away one of your best players on your team.
Once you offer the trade, go to the Career main menu and Advance to the next day. If there isn’t a popup showing that the trade was accepted, advance another day. Continue advancing until the trade is accepted or denied (it will most likely be accepted). Once there is a popup showing that the trade was accepted, click Finalize. Once you click this, advance one more day and the achievement should unlock.