. . . . I recorded a video with LED lighting. This caused some flickering . . . . .
In post editing - unfortunately not a lot you can do.
The only solution is to use LED lights that are designed for video work - these are designed so that the voltage applied to the LEDs is direct current so the light is emitted constantly.
With most mains (AC) operated, dimmable LEDs or pulsed current ie DC pulse width modulation lighting - the LED is actually pulsing faster than the eye can detect ie from 50 times per second up to several hundred times per second.
Through interaction with the video camera sensor scanning and framerate - in a simplistic view think of this as the number of still images per second recorded - and the pulsing light you get the flickering seen in the video.