How do I reset my arduino uno board?

I want it to forget the code I uploaded on it last week..

Load some other sketch.

PaulS:
Load some other sketch.

So I can just ignore it, work on something else and simply upload it?

void setup()
{
}
void loop()
{
}

Benny_Leonard:
So I can just ignore it, work on something else and simply upload it?

Yes. If ignoring an Arduino is possible. 8)