"error: failed to lock directory"- while installing

[AyushjGyawali]

Hi, The code that I ran to instal ggbilpot is : install_github("vqv/ggbiplot")

Then at first I get the error......

ERROR: failed to lock directory 'C:/Users/ayush/Documents/R/win-library/3.5' for modifying
Try removing 'C:/Users/ayush/Documents/R/win-library/3.5/00LOCK-vqv-ggbiplot-7325e88'
In R CMD INSTALL

Then when I go ahead and remove the file suggested above and re run the same installation code I get the error.....

*** installing source package 'ggbiplot' ...
Warning in file.copy(f, instdir, TRUE) :
problem copying .\NAMESPACE to C:\Users\ayush\Documents\R\win-library\3.5\ggbiplot\NAMESPACE: Permission denied
Warning in file(file, if (append) "a" else "w") :
cannot open file 'C:/Users/ayush/Documents/R/win-library/3.5/ggbiplot/DESCRIPTION': Permission denied
Error in file(file, if (append) "a" else "w") :
cannot open the connection
ERROR: installing package DESCRIPTION failed for package 'ggbiplot'

• removing 'C:/Users/ayush/Documents/R/win-library/3.5/ggbiplot'
  In R CMD INSTALL**

Please help. Thanks in advance.
Ayush