Your MAMP PRO 5 database data is located in
/Library/Application Support/appsolute/MAMP PRO/db/mysql
(NOT Users/Username/Library/Application Support/appsolute/MAMP PRO/db/mysql)
Specifically, your MAMP PRO 5 database data is in the mysql57 subfolder. Your may have other subfolders, such as mysql56_2018_XXXX, or mysql. These folders contain old database data from MAMP PRO 3 or MAMP PRO 4.
Individual Databases?
You can see the individual databases that you have created in MAMP PRO, they are in subfolders of the mysql57 folder. The folder name will be the same name as the database. Do not move these folders around. Any deletion or moving of your database data should be done using phpMyAdmin, or some other MySQL database administration tool.