How can I set my opened trade to close at 21:00 GMT?

Hi, I want to know, how to set my open trade so it will close automatically at 21:00 on certain date? The expiration section in pending order only close the trade if the trade is not open at certain time. However, once the trade is opened already, it won’t close unless it hit take profit , stop loss or closed manually. I already search at Google for this, but all I can find is a technique using complicated coding. I want it to be simple easy to understand.

I think you need to stick to complicated coding as you put it, pay a coder to create this for you is my best recommendation.

Some platforms have a one day futures contract eg. Daily FTSE100 etc. It is a one day only market that will expire at the end of the day either in profit or loss instead of rolling into the next day. Some of the UK spread betting companies do them (I used to work for one).

Otherwise what you are asking sounds simple but it is not. Most traders care a great deal what the price is before they will close the trade so you will needing some coding.