Part of the text output (and the first figure) is generated by the line
That is optional (it's only useful when debugging), so you can just delete it, or comment it out.
The rest of the text output comes from the call the the solver:
[x, xcost, info, options] = trustregions(problem);
You can reduce or suppress the amount of text output by specifying this in the options, as follows:
options = struct();
options.verbosity = 0; % 0 means no output at all; 1 means very little output; 2 is more etc.
[x, xcost, info, options] = trustregions(problem, , options); % the second input is the initial iterate; passing  tells manopt to use the default random initialization
You can find such information and more by typing
or by reading the tutorial
, specifically, the table under "Solvers" about the options structure.