Top layer pad with hole

I don't use Altium (and don't wish to!) but nevertheless, what you're requesting is unusual, and nearly all PCB manufacturers will automatically not give you what you want, even if Altium 2016 can do it.

If your top copper touches the hole, then PCB manufacturers (unless you confirm with them otherwise!) will automatically fill the hole with copper, meaning that the bottom of the PCB will definitely be in contact with metal.

Two ways around this are (1) discuss with the PCB manufacturer (and likely pay more, because it will be bespoke) or (2) simply don't have copper touching the edge. How you do that is really down to whether your software can do it or not.  KiCAD manages it fine, it's free, and up-to-date.

Not all PCB manufacturers will necessarily do this feature cheaply or cleanly. So I'd first advise that you find another engineering solution.

If it is necessary, I'd advise checking to ensure that "Automatically remove loops" is turned off in File > System Preferences: PCB Editor > Interactive Routing. Electrically unnecessary vias and traces usually get deleted by CS when this feature is enabled.

I solved a similar problem by just making a NP hole and then on the top layer using the circle/arc placement

and then adjusting the arc track width to the diameter that you want.

You then adjust the arc radius until it is slightly larger that the hole.

You will probably have to then reduce the arc width to suit.

I like your idea. I've tried to create the hole with a cutout but it don't work.

How do you make your hole ?

Thanks

Just make a hole/pad dia. 0.4mm and make sure it is unplated, like an unplated mounting hole.

Also, this part rings more alarm bells:

"My goal is to create a 0.8mm pad with a hole of 0.4mm."

Are you sure those measurements are what you need? If you do, then the "leaving a gap" method won't work, at least not with any practical PCB manufacturer. If those measurements are real, then the _only_ solution is to talk to the PCB manufacturer, because they won't be happy with the "leaving a gap" method. ("Leaving a gap" doesn't involve talking to the PCB manufacturer).

Out of sheer curiosity, why do you need this hole on the pad? Is it a test point for a multimeter probe or test fixture? If you need a via to get the signal to another layer, why not just tent the via?

No I just need to solder a wire that come from the other side of the pcb . The wire need to pass throught the metal and the pcb, and the pcb is glue to the métal . It is a led pcb

Given that, does the wire actually need to solder to a pad around the hole or could it extend a bit further to a pad on the board away from the hole?  That sounds do-able without stressing the PCB manufacturers.  With such a small hole, soldering the wire so close to it could well wick solder down and bridge to the metal plate.

Would it be possible to cut a groove through the surface of one of the blocks sides to sit the wire in (deep enough so it is flush, the wire can’t be too heavy gauge if a 0.8mm hole suffices) and bring it to the top of the board and a pad without using a hole? 

Unfortunately the LED is 3x3 and my PCB is a round 5.6.

I've found the solution. Making a circle to create the pad and I will make the hole by myself it is not a problem.