The Republic of Ireland strikerâ€™s departure leaves United one man light in the striker department.
Pardew told the Evening Chronicle: â€śLeon did a great job for me.
â€śBut the thing about Leon is that he needed regular first-team football.â€ť
And Pardew insists he could not guarantee the Nottingham-born centre-forward first-team action.
He said: â€śYou can only play a role where youâ€™re in and out of the team for so long.
â€śI felt it was right for him, and everybody concerned, that he moved on.â€ť