This blog post provides a piece of SQL that you can easily customize to check-for and remove a materialized view if it is present.
The SQL is;
v_MVName varchar2(30) := 'XXX';
for v_Row in (select 'x' from all_mviews am where am.owner = user and am.mview_name = v_MVName) loop
'drop materialized view ' || v_MVName;
In order to target a specific view just replace XXX in the second line with the name of your view.