You cannot. The i7 was not available in that model, and to change the CPU you would have to replace the motherboard as the CPU is not removable. And with another motherboard the best you can do is an i5. And the cost is around $200-300 plus labour. For a 5 year old system it would make more sense to put the money toward a new faster system.
-Forum Member since 2016 -I do not work for Dell -A user helping other users -If you like an answer please click on thumbs up -If a reply is a solution to your problem please click on Accept as Solution Gaming on a home built ASUS B450-F Gaming with Ryzen 5 2600X Real work on an Inspiron 15 5575