I have been taking. 5 ativan (lorazepam) twice a day for 3 weeks for anxiety as prescribed by my m.D. If I quit cold turkey will I have any withdrawal problems?

You will have it! Withdrawal sx would be somewhat dependent on the time you have been taking the ativan (lorazepam). Your med bio says you've been on it three weeks, so i would cut back to 1/2 twice daily, 1/2 once daily, and stop.
Stopping Benzos. Maybe. But, you do not have much of a history. But, there is no danger given your story for stopping abruptly.