issue deleting old OS SPA.pkg files

[itadmin]

I have been looking to update the OS on our Cisco WS-C3650-24PD running 16.12.3a, but there is no room in the flash.
So I looked to remove the old files but when I go to delete them I get this in return:

"#del flash:cat3k_caa-rpcore.16.09.05.SPA.pkg
Delete filename [cat3k_caa-rpcore.16.09.05.SPA.pkg]?
Delete flash:cat3k_caa-rpcore.16.09.05.SPA.pkg?
Warning: This system software is in use, deleting system file might cause system instability.
Delete of flash:cat3k_caa-rpcore.16.09.05.SPA.pkg aborted!
Please use "install remove file <filename>" to see if file can be safely removed.
"delete /force <filename>" can be used to force deletion."

I then looked at our boot and it shows below

"Current Boot Variables:
BOOT variable = flash:packages.conf;
Boot Variables on next reload:
BOOT variable = flash:packages.conf;
Manual Boot = no
Enable Break = no
Boot Mode = DEVICE
iPXE Timeout = 0"

From my (limited) understanding it means that it is using autoboot which goes off the last installed OS?

How would I go about changing to boot to be the current OS 16.12.3a only so that I can delete those older files to make room for the new OS.

[Leo Laohoo · Accepted solution]

There is a better way of doing this:  

request platform software package clean switch all

[itadmin]

Just want to confirm that it should be okay to complete this command when it says it was deleting "/flash/cat3k_caa-universalk9.16.12.03a.SPA.conf" which is related to the current OS.

/flash/cat3k_caa-guestshell.16.09.04.SPA.pkg
/flash/cat3k_caa-guestshell.16.09.05.SPA.pkg
/flash/cat3k_caa-rpbase.16.09.04.SPA.pkg
/flash/cat3k_caa-rpbase.16.09.05.SPA.pkg
/flash/cat3k_caa-rpcore.16.09.04.SPA.pkg
/flash/cat3k_caa-rpcore.16.09.05.SPA.pkg
/flash/cat3k_caa-srdriver.16.09.04.SPA.pkg
/flash/cat3k_caa-srdriver.16.09.05.SPA.pkg
/flash/cat3k_caa-universalk9.16.09.04.SPA.conf
/flash/cat3k_caa-universalk9.16.09.05.SPA.conf
/flash/cat3k_caa-universalk9.16.12.03a.SPA.conf
/flash/cat3k_caa-webui.16.09.05.SPA.pkg
/flash/packages.conf.00-
/flash/packages.conf.01-
/flash/packages.conf.02-
Do you want to proceed? [y/n]

W

[Leo Laohoo]

If you are currently on 16.12.3a, then yes.  IT is safe to delete the old files.

[itadmin]

/flash/cat3k_caa-universalk9.16.12.03a.SPA.conf which it wanted to delete was part of the current OS.
But I have run the command "request platform software package clean switch all" that has successfully cleared room and switch is still working as expected, thanks.