Can I delete old iOS installer files on my macbook? Is it safe to delete all the iOS installer files that are stored in my computer?

I have no more free space in the HD and I have seen that almost 16 GBs are used in old iOS installer. In the case I delete those file will have problem in the future for backup or restore procedures?
iOS installer files (IPSWs) can be safely removed.

IPSWs are not used as part of the backup or backup restore procedure, only for iOS restore, and as you can only restore signed IPSWs the older IPSWs can't be used anyway (without exploits).

You can always re-download IPSWs from Apple's site if you need them in the future.