Clarification about changing from POP to IMAP

I would like clarification about changing Thunderbird email to IMAP. On one of my devices I use POP to access my email accounts, other devices use IMAP. The POP account is set to NOT delete email from the server so all the emails I need are still on the server. Am I correct that if I delete the POP email accounts from Thunderbird the emails stored on the device will be deleted but still be left on the server. So I can just delete the POP accounts from Thunderbird and then add them as IMAP without losing emails from the server.