Switched mode power supplies don’t like being turned on and off repeatedly but a good quality supply should be OK Why are you asking this question as turning off the computer at the supply after you have shut down is normal use and should not cause any problems? The alternative of leaving the computer powered up all the time after you have shut down will cause the power supply to have a shorter life and cost more in electricity.
oh because when i turn off the computer there is a green light on the back of the power suplly meaning power is flowing. so i turn of the light switch which to completely shut the power off. wil that reslut in a shorter power supply life?