Latest questions about "storage problem"

I have edited my clips and now when I hit the convert all button a pop up screen comes up and says "There is not enough space available to convert all the files selected and I need to clear some...

I loaded 119 GB on a 1 terabyte external drive. Now the disk indicates to be full. How can I clear the space?

My Lava Iris 402 always shows that memory is full. What can I do to fix that? I can't install the apps directly to memory card.