Ok before I start telling you the problem I'll have you know that I have :

Learned sport Taekwondo for 4 years
Learned brawl Taekwondo for 2 years
Learned Ninjitsu for 1 year
Worked out at the gym for 1 year

Ok,the problem is that I am really big for my age,I'm 13 and a half years old and I am 179 cm high without my shoes, have wide shoulders and I weigh 81 kilograms,now the real problem is that I am superior in strength to other people of my age but I lack in speed when it comes to general movement in a sparing match.I have tried running 2 miles every day and I can beat anyone at running but that didn't improve my battle speed.
Any ideas as to how I could improve it?

I would sugest taking up a sport like tennis or baseball where you have to run and catch or hit a ball
Or just go to a batting cage and hit balls start at a slow speed till you become good at hitting the ball and then work your way up to faster speeds it will help your speed

Sometimes it is better to allow yourself to grow, and develop naturally, do not be in a hurry to be superior or better, but earn your way.

There are ways to make you faster, but I am not sure you have the maturity or mind set to listen or learn that being able to beat everyone up does not make you better it just makes you win all the time. Winning all the time will not cause you freedom or improvement in other areas, it can only do what it can do. Do not be in a hurry to be great, be what you are. Be satisfied that you have learned as much as you have, and are well on your way to being well rounded, and capable in fighting.

But if you must, if you stop trying to win, and do it, you will be faster. Life is not "how to" but "actually doing". Do not try to hit them, just hit them.
As yoda pointed out, there is no try. Effort is not an effect, it is a reaction to what you want to happen, not to what is going to happen.

Many martial arts can teach you speed, but I do not know if you or anyone on this web site is ready for such knowledge. Be well. Be safe. Trust.

https://www.askmehelpdesk.com/martial-arts/speed-power-34987.html

Read that then it will come.