Is it necessary to get a urethral cyst removed if it does not cause any symptoms?

No. Treatment of urethral cysts depends on location and if they are causing symptoms. If the cysts are around or near the urethral meatus and not causing discomfort or interfering with voiding then they generally do not need to be treated. A urethral diverticulum is not a true cyst but a weak point in the urethra wall which may need treatment if it contributes to infection. Get your doctor's advice.