Appending pairs of columns in Google Sheets

I have a table in google sheets with multiple data like this:

I need a formula to make it that way:

Note that keeping the order is not necessary, I just need all the data in two columns.

I’ve tried messing with Arrayformula but couldn’t do it.

Any ideas here?

>Solution :

If you have only 4 columns then could try-

={FILTER(A2:B,A2:A<>"");FILTER(C2:D,C2:C<>"")}

If you have more columns then you can add those into curly brackets.

Or using QUERY() function.

=QUERY({A2:B;C2:D},"where Col1 is not null")