To find out how much space Robert will have left after using the squares, we start by calculating the area of one square. Since each square has a side length of \( s = 7 \) inches, the area \( A \) of one square is given by:
\[ A = s^2 = 7^2 = 49 \text{ square inches} \]
Since Robert is using 10 squares, the total area covered by the squares is:
\[ \text{Total area of squares} = 10 \times 49 = 490 \text{ square inches} \]
Now, we will subtract the total area of the squares from the area of the poster board:
\[ \text{Remaining area} = 720 - 490 = 230 \text{ square inches} \]
Thus, the amount of space Robert will have left for his presentation is:
\[ \boxed{230} \text{ square inches} \]