delete zfs and snapshots from upgrade process?

Hello,

I have make an upgrade from 13.1 to 14.1. 
uname -a 
FreeBSD ftc 14.1-RELEASE-p3 FreeBSD 14.1-RELEASE-p3 GENERIC amd64

Everything works fine. 

My question:
There are some zfs and some snapshots. Can I destroy them or are they
required?

Here is the list:
zfs:
zroot/ROOT/13.1-RELEASE-p9_2023-08-27_201128
zroot/ROOT/13.1-RELEASE_2023-08-27_195317
zroot/ROOT/13.2-RELEASE-p12_2024-08-24_192252
zroot/ROOT/13.2-RELEASE-p2_2023-08-27_223329
zroot/ROOT/13.2-RELEASE-p2_2024-08-24_185205
zroot/ROOT/14.1-RELEASE-p3_2024-08-24_192543
snapshots:
zroot/ROOT/default@2023-08-27-19:53:17-0
zroot/ROOT/default@2023-08-27-20:11:28-0
zroot/ROOT/default@2023-08-27-22:33:29-0
zroot/ROOT/default@2024-08-24-18:52:05-0
zroot/ROOT/default@2024-08-24-19:22:52-0
zroot/ROOT/default@2024-08-24-19:25:43-0

Franz