Diagnosis
That's not a smudge on the outside lens. What you're seeing is either dust or a tiny fiber that has gotten inside the projector and has settled on the main internal optical component, casting a shadow onto your image.
How to Fix It
Unfortunately, there's no safe user-serviceable way to open the Leisure 3W and clean inside the optics. Your best bet is to try to dislodge the debris. 1) Turn the projector off and let it cool. 2) Gently pick it up and, while keeping it level, tilt it slowly in different directions, then tap the side *lightly* with your palm. The goal is to get the speck to fall off the internal lens or prism and out of the light path.
If That Didn't Work
The blob's position on the screen might change if you use keystone correction to digitally shift the image, but this will degrade overall picture quality. It's a trade-off.
Heads Up
This is a common issue with lower-cost, sealed projectors. Avoid using the projector in very dusty environments, and never try to blow air directly into the lens opening with compressed air, as you'll just force more dust inside.