Linking problem with sdl2

[Robertorosmaninho]

I tried to stall sld2 on my MacOS Mojave and it returns the following error:

Error: The brew link step did not complete successfully
The formula built, but is not symlinked into /usr/local
Could not symlink lib/cmake/SDL2
/usr/local/lib/cmake is not writable.

You can try again using:
brew link sdl2

Then, when I tried to link again:

MacBook-Air:~ $ brew link sdl2
Linking /usr/local/Cellar/sdl2/2.0.10...
Error: Could not symlink lib/cmake/SDL2
/usr/local/lib/cmake is not writable.

How can I fix this?