I guess you have to backup your G Suite data some place safe. My advice is to use Google Takeout. It allows you to archive your mailbox and other data items into local folder. For using Google Takeout, you can follow the steps given below.
Login to Google account
Go to My Account >> Control your Content >> Create Archive
Choose Archive format, size & delivery option
Click on Create Archive
For more info, you can refer this link:
Google Takeout file Converter