problem with Arduino Leonardo

I didn't remenber to put the sketch into a "while()" and now when I connect it to the computer and try to upload a new sketch arduino do not respond because its busy sending information though the USB. What can I do now to "rescue" arduino leonardo?

Press and hold the Reset button.
Upload a new sketch from the IDE while holding the Reset button.
When the IDE shows Uploading, release the Reset button.

I have tried that but it says: " avrdude: usbdev_open(): did not find any USB device "usb" "

The only time I have ever seen that is when you are selecting “Upload Using Programmer Ctrl + Shift + U”

You need to select the Upload icon or use Upload Ctrl + U

yes you are right, but the arduino leonardo is trying to connect with the computer to send information, so my question is, how can I clear arduino´s memory to stop the link with the computer? Is it possible or I have to thow it away?

When you release the reset button, the bootloader will run for several seconds waiting for a new sketch. If it times out, the sketch in firmware will run. This is why you need to hold the reset button until you see Uploading in the IDE. The upload process should find the Leonardo bootloader and upload the new sketch.