If you like the shape with the two branches at the top and they are well balanced, I'd leave them and just remove all the other branches lower down the main trunk. The upper branches should spread naturally with time without any pruning needed.
@alastair_19 Only by removing one of the forks which would leave th etree unbalanced.
I agree with @Plantminded. It has a good shape already so leave the top alone and just keep the main trunk bare so all the energy goes to the top branches. With time it will mature and fill out and make a lovely tree.
Vendée - 20kms from Atlantic coast.
"The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
In my experience, once the leader has gone, that's it. I have two trees like yours in my garden where the central leader has gone, creating two main branches. They have developed a good shape and size for my small garden. If you want a taller tree with one main leader, I think you're going to have to replace it. Some people try to remove one of the two branches like yours and train the remaining one to be the leader but I think it looks odd unless you start this process at an early stage.
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I agree with @Plantminded. It has a good shape already so leave the top alone and just keep the main trunk bare so all the energy goes to the top branches. With time it will mature and fill out and make a lovely tree.