This function deletes all parenthesis from a character vector that has a numeric value inside. This is applicable as THETA(n), ETA(n), DADT(n) is not always allowed in R coding
Examples
par_delete(c("LOG(1)","ETA(1)","EXP(2)/ETA(3)+THETA(4)"))
#> [1] "LOG(1)" "ETA1" "EXP(2)/ETA3+THETA4"
