How to delete or merge a partition in APFS

[CooperBox]

I'm still trying to get my head around some of the subtilities (or some may say annoyances of APFS).
I have a 15" MacBook Pro and want to do a clean install of Catalina. It's currently running Mojave which has two APFS partitions, one for the OS and another named 'Data' for downloads, docs etc.
To facilitate a clean install of Catalina, I prefer to delete the 'Data' partition, or if possible merge the empty space into one single partition, and then perform a clean Catalina install on it.
Never had a problem with HFS+, but as you can probably tell APFS formatting, deleting partitions etc has me confused.

 

[Toledospod]

I'm still trying to get my head around some of the subtilities (or some may say annoyances of APFS).
I have a 15" MacBook Pro and want to do a clean install of Catalina. It's currently running Mojave which has two APFS partitions, one for the OS and another named 'Data' for downloads, docs etc.
To facilitate a clean install of Catalina, I prefer to delete the 'Data' partition, or if possible merge the empty space into one single partition, and then perform a clean Catalina install on it.
Never had a problem with HFS+, but as you can probably tell APFS formatting, deleting partitions etc has me confused.

The following article from Apple might help to understand the difference between Partitions and Volumes - https://support.apple.com/guide/disk-utility/partition-a-physical-disk-dskutl14027/18.0/mac/10.14

It's odd that you have the data and the HD, this is normally something Catalina does when you upgrade from Mojave (has to be APFS to do that so it takes care of that when you upgrade). Up until Mojave, all data and the OS was always on just the one volume called 'Macintosh HD' (or whatever you call it on your machine).

When you say clean install, do you mean erasing and reinstalling MacOS?

 

[CooperBox]

The following article from Apple might help to understand the difference between Partitions and Volumes - https://support.apple.com/guide/disk-utility/partition-a-physical-disk-dskutl14027/18.0/mac/10.14

It's odd that you have the data and the HD, this is normally something Catalina does when you upgrade from Mojave (has to be APFS to do that so it takes care of that when you upgrade). Up until Mojave, all data and the OS was always on just the one volume called 'Macintosh HD' (or whatever you call it on your machine).

When you say clean install, do you mean erasing and reinstalling MacOS?

Thanks for reply. Yes, the idea is to erase Mojave and clean install MacOS Catalina.

 

[Taz Mangus]

Thanks for reply. Yes, the idea is to erase Mojave and clean install MacOS Catalina.

Might be easier to just backup the Data Volume, erase the physical device, install Catalina and migrate the backup of the Data Volume to your Catalina install.

 

[Toledospod]

Might be easier to just backup the Data Volume, erase the physical device, install Catalina and migrate the backup of the Data Volume to your Catalina install.

That's what I was thinking of when the OP stated a clean install, but I wasn't sure. If you need to backup, then Taz's suggestion would work just fine.

Hope this helps!

 

[CooperBox]

Thanks for all your help.