How to delete photos from my photo library on an iPhone 4?

Hi everyone well i have photos in my photo library and i want to delete them but the photos are not deleting. Like if i click that bin thing on the bottom right corner when i click on the photo if i want to delete it, it won't do anything. I don't even know how the photos were put in my photo library but i really want to delete them. They're just random photos i had from like a year ago but i can't get rid of them. I've heard if you sync your iPhone to iTunes then you can delete them but well i don't know how to sync my iPhone like when i plug it into the computer it doesn't automatically sync so if you know how to sync your iPhone could you please comment that too. I know there's an option under 'Photos' and it says 'Sync photos from' and then it says like choose folder, but what do i do from then? I hope this is not confusing what my problem is, but if you know how to delete photos from your photo library from an iPhone 4, can you please comment below how to do it. The photos are just a waste of storage and they're not important so it doesn't matter if they are permanently deleted.
P.S i have updated my iPhone to ios7.

The most likely cause for this bug is an OS malfunction, easiest way to fix it is to turn off your iphone, wait atleast 10 minutes or so, and then turn the phone back on again. This method allows the phone to reboot itself and, in most cases, fixes errors within the system.

In addition to turning the phone off and then on again, have you updated to IOS 7.1? It was released literally days after IOS 7 and would most probably fix any bugs you were having with your phone. I would highly recommend you update if you can, and you can do it wirelessly using a Wi-Fi connection.

Syncing your iphone to your computer requires itunes, so make sure you have that downloaded before you do anything. The best way to see if your computer has recognized the phone is to open my computer on PC, or finder on mac, and you should see the phone as an eject-able disk, like a USB would appear. If your computer doesn't recognise your phone, you need a new connector cable, if it does, open up itunes to see if it has synced. Give it some time, the phone might need to charge and your computer might not be powerful enough to sync straight away. After 10-15 minutes, restart your computer and re-open itunes. If still no response, restart your phone while it is connected to the computer.finally, if you still have no sign your phone is syncing, re-download itunes from the apple website, ensuring your get the latest update.

Hope this helps and good luck.