Destroy terrain after camera pass for more performance ?

Hello ,I am currently working on my first unity project, a simple 2d car (Hill climb ) base game . So i want to ask if i need to destroy terrain after the camera pass for a better performance in a future android build or or I have to leave it like that . If I have to destroy it, how could I do it ?

 

Fairly certain unity has many optimizations that will make your rendering speed fine no matter what you do. Objects off screen do not get rendered and dont take up gpu etc. Its still good practice to clean up unused data but i wouldnt worry too much about it for your example.