How can I move two levels up from my current working directory to display a pdf that I am generating with an rmd file inside a function? for instance, my working directory is: C:/Users/Desktop/IBT but since my pdf is printed at C:/Users/Desktop/IBT/inst/rmd. I am using browseURL to display the pdf file but is not finding it because it thinks the pdf file is in my original working directory. I basically want browseURL to look on C:/Users/Desktop/IBT/inst/rmd. This is what I got below:

pdf_doc <- function() {
  library(shiny)
  library(rmarkdown)
  
 olddir <- getwd()  #Save original working directory

  rmarkdown::render(input = system.file("rmd/mydoc.Rmd", package="mypackage"),
                    output_file = "mydoc.pdf")

  setwd('..')              #Move up one level(go backwards)
  setwd("./inst/rmd")      #Change dir to tell browseURL where the pdf is.
  browseURL('mydoc.pdf')   #display pdf file
  setwd(olddir) #Go back to original working directory
}

#display mydoc.pdf
 pdf_doc()

#I get the error below:
Error in abs_path(input) : The file '' does not exist.
In addition: Warning message:
In normalizePath(path.expand(path), winslash, mustWork) :
path[1]="": The system cannot find the path specified