Dhcp not working correctly after global rename

I currently renamed my pc’s on the network and after doing so I noticed alot of people not pulling the correct ip addresses. the address it would pull was a 192.168.123.xx the network we are currently on is a 10.1.10.xx. my thought is that we are running out of ip addresses because it is still holding the old computer names in the dns. is there a way to start that over to possibly get rid of the old and in with the new? thank you in advance for any time you put into this…