Deleting info on mobile phones

As suggested you can get a set of adapters and cable cheaply or donate to security . govt, police etc.
Will they access your info?
Anyway do not accept the restore to default settigs.

If you can connect to computer and should come up as external storage drive. Use one of the many deleting programmes. I think some freely available online or even your firewall/virus programme and use this to delete your info, preferably more than one pass.

I suggest you do this when selling your computer also.