Fresh start with MAC

I have recently moved across the country and want to start fresh with my data. (big difference between Colorado and Florida). How do I remove the past data from my Mac and start with a clean slate? I am planning on using the Mac version of WD this go round since I will be using the API from Ecowitt. Vs using the Windows based software I used in CO that developed a hickup just prior to moving. The Mac I am using has speratic old data from Colorado on it as I experimented with it for several items over the years.

Thank you in advance for any help.

Greg Allshouse