It can be, but remember Tecoma Sans will send up new growth from the base. Heres a link that might be helpful on your pruning

Here is a link that might be useful: Pruning Tecoma Sans

I agree with Turtle as usual. It can be done, but they do re-sprout a lot from lower down, so it will be a lot of maintenance to keep it as a tree shape. If you just want the screening, it will still screen just as much in its natural shape and won't need as much work to maintain it.

Of course, some folks love trimming plants, and in that case, go for it.

Let us know what you decide and how it works out. Great link too, Turtle.

Take care,
Grant

Why not add a trellis and plants some grapes or a pomegranate?

How about trying Mexican Bird of Paradise (Caesalpinia mexicana) instead? It can easily be trained into a small tree form and has colorful yellow flowers nearly year round.

Here is a link that might be useful: Mexican Bird of Paradise