Usually closing that window, or resarting R or RStudio session works, as FJCC said. Since that's not the case with you, I'm going to give 3 suggestions, but please note that these are just guesses on my part.
- Update your
RStudio. The current version is 1.2.1335, and your version 1.0.136 is very old.
- Run
dev.off() a few times, and then try to plot again.
- Run
options(device = "RStudioGD"), and try to plot again.