SAS prints graphics by default. This can be suppressed by:
ods graphics off;
To suppress printing specifically of PROC REG, add the following to the PROC REG statement:
MAXPOINTS=NONE | max <heat-max>
suppresses most plots that require processing more than max points. When the number of points exceeds max but does not exceed heat-max divided by the number of independent variables, heat maps are displayed instead of scatter plots for the fit and residual plots. All other plots are suppressed when the number of points exceeds max. The default is MAXPOINTS=5000 150000. These cutoffs are ignored if you specify MAXPOINTS=NONE.