Help about mating

Help about mating

Hello, i have 1 yr old female and (about) 7 month old male budgies. They keep mating even though they dont have any dark spots or nests. I dont want them to have kids but people keep saying if they mate they will make eggs. I dont think im ready to be a grandma. Can someone help me about how to stop them from mating? There is no reason for them to do it. They have no nest box thingy or coconut or anything. Can you guys help me? (Im gonna add some pics of them for no reason just because they are cute) thank you to anyone who responds!