Hi,

Unchecking a group means to remove a user from the user group. You can achieve this using Python code.
 group_e = self.env.ref('module.odoo_group')
 group_e.write({'users': [(3, self.env.user.id)]})

Also you can change the values accordingly by looking this,

0, 0, { values }) link to a new record that needs to be created with the given values dictionary

(1, ID, { values }) update the linked record with id = ID (write values on it)

(2, ID) remove and delete the linked record with id = ID (calls unlink on ID, that will delete the object completely, and the link to it as well)

(3, ID) cut the link to the linked record with id = ID (delete the relationship between the two objects but does not delete the target object itself)

(4, ID) link to existing record with id = ID (adds a relationship)

(5) unlink all (like using (3,ID) for all linked records)

(6, 0, [IDs]) replace the list of linked IDs (like using (5) then (4,ID) for each ID in the list of IDs)

Hope it helps