Packrat/init.R error preventing me from installing packages

I received the following message when I tried to install a new package via CRAN:

In file(filename, "r", encoding = encoding) :
  cannot open file 'packrat/init.R': No such file or directory

After attempting to figure out what was going on with packrat, I uninstalled packrat but received the same message. I then proceeded to sequentially: uninstall RStudio, uninstall R, manually deleted the RProfile files along with every other R-related file in my /usr/ and /etc/ directories. Then I reinstalled R, and upon opening the newly-reinstalled R for the first time, two things happened:

  1. The packrat error message above;
  2. Error messages like this:
Warning: namespace ‘leaflet’ is not available and has been replaced
by .GlobalEnv when processing object ‘pal’

for leaflet, scales, ggplot2, lazyeval and plotly, with the "processing object" differing. Those packages are not even installed (since I just reinstalled R), and when I try to install them I get the packrat error above.

What do I need to do to fully purge the "memory" of packrat and packrat/init.R , so I can go back to being able to install packages? Or, how do I "make peace" with packrat? Before removing and reinstalling everything, I was unable to install anything new. Now I am at a complete standstill because I can't install anything at all. I'm on Linux Ubuntu.