WITH t AS (SELECT 'aaa <b>bbb</b> ccc' AS teststring FROM dual)
SELECT
teststring,
regexp_replace(teststring, '<.+>') AS reg1,
regexp_replace(teststring, '<.*>') AS reg2,
regexp_replace(teststring, '<.*?>') AS reg3
FROM t
TESTSTRING REG1 REG2 REG3
aaa <b>bbb</b> ccc aaa ccc aaa ccc aaa bbb ccc