To clean a power strip, start by unplugging the power strip and then unplugging anything that is plugged into the power strip.
Next after the power strip is unplugged you can take a soft cloth and get it slightly damp with some water and mild detergent and wipe the power strip down.
You can also use some rubbing alcohol or vinegar to clean the power strip with.
Just avoid getting any water or soap or rubbing alcohol or vinegar inside the power strip.
If you do get any liquid inside the power strip, be sure to turn the power strip upside down and allow it to dry out fully before plugging it back in.
Don't immerse the power strip in water or spray the power strip directly.
After you clean the power strip, ensure the power strip is completely dry before you plug it back in again.
Dip a cloth in some cleaning solution such as dish detergent and water or a degreaser or some vinegar and then wring out any excess moisture and then gently wipe the power strip surface down.
For really stubborn stains on the power strip you can use a small amount of rubbing alcohol on a separate cloth, but avoid getting any of the rubbing alcohol near or in the electrical contacts.
After wiping the power strip down, rinse the cloth with clean water and then wipe the power strip down again to remove any soap or other residue.