Hello and welcome to Apple Support Communities Michelel21,
Thank you for contacting us. You have come to the right place and we are happy to assist you. We understand you have deleted emails from your watch, which also deleted from your iPhone. We can understand why you’d reach out for a solution. To start, make sure you have the most current operating system on your device. (Settings > General > Software Update) Here is a good article about deleting and recovering emails: Delete and recover emails in Mail on iPhone
Make sure you have backups prior to making any major system changes: How to back up your iPhone, iPad, and iPod touch
Thank you for contacting Apple Support Communities.
Best regards.