All what you need to do is to use
REPLACE[
^] function ;)
Have a look at below example:
DECLARE @tbl TABLE ([Value] INT, String VARCHAR(MAX))
INSERT INTO @tbl ([Value], String)
SELECT 1, 'Fruits - Apple, orange, Mango ; Flowers - Rose, Lilly, Lotous'
UNION ALL SELECT 2, 'Fruits - orange, Mango ; Flowers - Rose, Lotous'
UNION ALL SELECT 3, 'Fruits - Apple, orange, Mango'
UNION ALL SELECT 4, 'Fruits - Apple, orange, Mango ; Flowers - Rose'
SELECT [Value], REPLACE(REPLACE([String], 'Fruits - ',''), ' ; Flowers - ', ', ') AS String
FROM @tbl
Result:
1 Apple, orange, Mango, Rose, Lilly, Lotous
2 orange, Mango, Rose, Lotous
3 Apple, orange, Mango
4 Apple, orange, Mango, Rose