Let's say you have created a snapshot, you have used it and now you want to remove it.
What you can do if you get the following message?

core:~# lvscan | grep mylv
  ACTIVE   Original '/dev/datavg/mylv' [2.00 GiB] inherit
  ACTIVE   Snapshot '/dev/datavg/snapmylv' [1.00 GiB] inherit
  
core:~# lvremove -f /dev/datavg/snapmylv
  [color=red]Can't remove open logical volume "snapmylv"[/color]

One way is to ask dmsetup for help:

core:~# [color=green]dmsetup -f remove /dev/mapper/datavg-snapmylv[/color]
core:~# [color=green]dmsetup -f remove /dev/mapper/datavg-snapmylv-cow[/color]
core:~# [color=green]lvremove -f /dev/datavg/snapmylv[/color]
  Logical volume "snapmylv" successfully removed

core:~# lvscan | grep mylv
  ACTIVE            '/dev/datavg/mylv' [2.00 GiB] inherit

If I will find other ways, I will write here.
DONE!