Your idea has been asked before.
I would say it has been asked maybe a hundred times over the 2+ years I have played this game.
The Players in the community have always loved the idea of GH reset.
All the posts which have ever been made about GH Reset have been upvoted.
The road block is with the game.
Plarium simply doesn't want to do the suggestion.
In the past, A moderator said a reset button for GH wasn't needed.
The moderator said any mistakes you make will correct themselves when you max out your GH.
I don't know if this statement was the moderator opinion or if it was the offical response from the managers/developers as to why they didnt want to implement this idea.
Regardless of the above, The statement given does have merit.
Any mistakes you make in GH will correct themselves when you max the GH.
The only problem is it takes a long time to max the GH.
I will give you an upvote just like all the other threads which had same idea.
Just don't put all you hopes on this idea being done.
Check out the GH Guide I wrote in Guide section of the forums
It can help you avoid further mistakes in the mean time.