Is it permissible for the property owner to take a commission (brokerage fee) on his property when selling or renting it, considering that real estate offices take 2.5% of the value of the rent or the property?

Brokerage is intermediation between the seller and the buyer, and it is generally permissible as long as it does not involve assisting in a prohibited sale or pointing to something whose sale is forbidden. There is no harm in the property owner taking a commission when selling or renting out their property, and this commission is calculated from the price or rent.