I cant find a way to prevent team members to delete a task or change the name and due date. I tried to give them commentor access only, but when i assign them the task, they are able to change it. This is no bueno
Welcome to the Asana Community Forum @Alex_Palma 
The comment access for a project applies to all tasks except the ones that are assigned to the person directly. When a task is assigned directly it will also show in My Tasks which means you can amend more things. I did some tests around comment access only and task assigning recently to see how things are impacted, such as custom fields also.
In regards to due date changes what you can do is set up a rule that triggers whenever a due date is changed. This way you might be able to monitor better.
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