If you signup to Mashvisor using a Google Account, then all you have to do is to click the "Log in with Google" option and choose your Google Account to sign in. In this case, resetting your password won't be possible as your Mashvisor account will use the same login info for your Google Account.

If you signup to Mashvisor using a normal email, you can click the "Forgot Password" link on the sign-in screen and send a password reset request to your email address.