Reasons to destroy wild dinos
1) Lag and low fps because there are too many wild dinos in an area
2) There was an update with dino species and you want them to spawn in quickly
3) You've got something very dangerous like a giga near your base and you need a safe way to get rid of it.
Before you try to kill everything I recommend backing up your game just in case something goes wrong. You also don't want to be in the middle of taming something. To enter the command in single player
How to Kill all the Dinos I Ark Survival Evolved single player
1) Hit the tab key to bring up the console
2) Type enablecheats then hit enter
3) Hit the tab key to bring up the console again
4) Type destroywilddinos and hit enter
On Xbox and Playstation
PlayStation L1 + R1 + Square + Triangle (hit the buttons at the same time)
Xbox LB + RB + X + Y (hit the buttons at the same time)
The game could lag very badly, or freeze for a few minutes like it did on my PC. Then all the creatures should be brand new.
I have this same problem, but with fish, near our base on the Xbox one version, and will have to give it a try.