How can we limit showing certain dimensions on dimension tree?
i have 4 dimensions created, however i would like the dimension tree to show only one on it.

The Dimension tree gadget takes a parameter - dimension.

So if what you need is to limit the tree gadget to displaying one Dimension, you can limit it either by default or by user, for each Scorecard, on any Dashboard where you have added it for use.

In 5.3.1 the Gadget will also automatically filter out any Dimensions that don't make sense for a particular Scorecard, to avoid users selecting a Dimension filter and then discovering no Measures are linked to it.