I tried using the manual cut and paste technique but the photos seems to "reappear" at my phone. Any techniques or free software to help with the transferring process? Thank you sifus!

There are two quick methods:

Connect your mobile device and open iPhoto. On the left side bar you will see "Devices" select the mobile device you want to clear. Once you have selected the device it will informed the xx amount of photos are already saved, at this point you will have the option to delete the already imported photos. You might find this option on the center-right side of the screen or bottom right corner depending on OSX and iPhoto Version.

Open image capture, this software allows you to delete/import all images from a camera/mobile device at once. Be aware that this option is only recommended if you are certain all your images have been saved. Once image capture loads all the previews for your specific mobile device Press "Command" + "a" to select all. Once all the images are selected in blue, look for the the red delete button \U0001f6ab on the bottom left corner. This will be the fastest way of deleting and importing, but it does not keep track of what has been uploaded in the past.