How to delete pics off my iphone?

I have 2 albums on my iphone 5s ios 8.1 that won't delete. I can't delete individual pics or the whole album. How do i get this off? Do i need to plug it in the computer?

Wait for a window to open (Auto Play window) and select "Open Device to view files". Next will appear the iPhones' "Internal Storage" icon. Click it and see "DCIM" and click it. Then click on the next folder icon that appears. You will see a bunch of "IMG" files. Click on either file to view. You may right click on any IMG and left click and select either "Open' "Cut" "Copy" "Delete" or "Properties". You may also click outside edge of any IMG hold the right click and drag the cursor down or up to shade multiple IMG's then right click on any shade area and select "Delete". While an IMG is clicked on, hold the click and drag to the desktop or drag to a folder to save or them… Into. Once the IMG or Video is save to the desktop, you may right click on it and rename it.