Louisiana Tech athletic director Tommy McClelland made the announcement Friday.
DeMoss has 38 years of coaching experience, the past two coming at Louisiana Tech, her alma mater. She was part of six national championships at Tennessee and coached at Kentucky and in the WNBA with the Indiana Fever.
McClelland said a national search would begin soon.
"As I said earlier, I have not gotten into hiring mode yet," McClelland said Friday. "I need an opportunity, me personally, to be able to collect my own thoughts and evaluate some things as we move forward and, quite frankly, focus on our student-athletes right now and give them the support that they need."
Tyler Summitt, 25, had just finished his second season at the school.
"It is with great regret that I resign from my position as head coach of the women's basketball program at Louisiana Tech University," he said in a statement released by the school Thursday. "I am profoundly disappointed in myself for engaging in a relationship that has negatively affected the people I love, respect and care about the most."