請問dbSetCellPortTypes 定義過的port 要如何remove？

例如：
dbSetCellPortTypes "VIR_LIB" "VIR_CELL" '(
("VSS" "Inout" "Ground" )
("VDD_CO" "Inout" "Power" )
("VDD" "Inout" "Power" )
("PAD" "Input" )
("O" "Output" )
) #f
我要把VDD這個portremove 掉！

重新load一遍新file即可，
#t 还是 #f 不记得了，

不行耶！
dbSetCellPortTypes "VIR_LIB" "VIR_CELL" '(
("VSS" "Inout" "Ground" )
("VDD_CO" "Inout" "Power" )
("PAD" "Input" )
("O" "Output" )
) #t