I have imagery with high resolution .5m, large parts covered with clouds, so it's obscure many urban areas.
How can I remove the clouds?
You can't 'remove' clouds from optical imagery, what you see is what you get; they are photographs and there is no optical data recorded from below the clouds in the same way that there is no data underneath building roofs.
If you use remote sensing data of a longer wavelength than light such as microwave, the water particles in the clouds do not absorb the energy from the sensor, but this type of platform is typically of a lower spatial resolution than optical imagery, and is consequently used for different tasks, such as soil moisture estimation and surface roughness estimation.
The only solution as such is to try to find a satellite pass without clouds and combine all the clear segments of your study area to make a full clear coverage.