It is a point in the page to jump to from a link eleswhere in the same page or other pages and is attached to an object in the web page.
To remove the anchor point, right click the object the anchor point was added to, select Web properties, Link tab and set it to Do nothing. Then apply an anchor point to the object in the location where you want to jump to in the page
An object can be anchored to text, so that the object will move to remain at the same relative position during editing.
Right click the object anchored and select the Anchor to text option again - this will toggle it off
That's not what I meant. For example if I draw a circle, there will be 4 anchor points with handles. If I wish to alter the shape of the circle but only want one of the handles to move without changing the opposing handles position, how do I do that.
. . . . only want one of the handles to move without changing the opposing handles position, . . .
Using a circle as an example either using the Selection tool, or still in the Shape tool the opposing handle does not move as shown in the example below
If you are wanting to stretch, for example the top half of the circle, leaving the bottom half as a semicircle ie to create an ovoid this AFAICS is not possible, and you have to resort to combining shapes.
I will tag in @browj2 as he is a regular user of Xara Designer.
Those are not called anchor points, just points or handles.
To edit a shape using the Shape Tool, select the shape, right-click, Convert to editable shapes, select the Shape Tool and edit, add/move points, etc.
EDIT
In the image below, the upper left shape started as a circle. The second one, the circle, was just converted to shapes and you can see a bunch of handles that just became available. Using the Shape Tool, you can add/remove/adjust points and use the handles to change the curvature at a point.
No, not even. They simply call it the "Center." If you click on it, the values box changes from Width and Height to Center. As far as I have found, you cannot move the centre from its position like the anchor point in VPX/MS. There should be no need as one is not making an animation.
For example, with a rectangle, it you want to change the size, you can drag a side handle and the size increases from the centre, similar to what MEP used to do.
The anchor point is linking an object to a particular point - like anchoring to text.