One way ..

Assume the numbers are in col A, in A2 down

Put in B2: =IF(COUNTIF($A$2:A2,A2)>1,"X","")
Copy B2 down

This'll flag all duplicates in col A with an "X"

Now do a Data > Filter > Autofilter on col B
(put a label in B1 first)

In the droplist in B1, select "X"

This filters out all the duplicate rows

Select the row headers for the duplicates
(this will be all the "blue" colored filtered row headers)
Right-click > Delete Row

Remove the Autofilter