Even though he is a great player but that was in the past and if there is very little contribution so no reason to keep him, will it benefit the team? clubs have to take into account the money that must be spent to pay him and it is not a small value, if releasing Ronaldo actually has a good impact on the clubs and maybe for Ronaldo himself then it is a good thing for both
I think it's a good option for both. This choice will not harm one party. Cristiano Ronaldo's performance is no longer the same as it used to be even though he continues to work hard to be able to perform optimally in every match.
We can see in some of Manchester United's games he failed to take good chances to score.
In my opinion, a player who plays as a striker, aged over 30 years is no longer performing optimally. Unless the player plays as a CB like Raul Albiol and Thiago Silva.
Considering Ronaldo who is now 37 years old, Ronaldo and Manchester United should consider the options as you say for the good of both.