Rule Definition
Every index increases the time it takes to perform INSERTS, UPDATES and DELETES, so the number of indexes should not be too high. Try to not use more than a maximum of 4-5 indexes for one table. If you have a read-only table, then the number of indexes is not as important and thus may be larger.

Remediation
Drop unecessary indexes.

Violation Code Sample

-- SQL Server Sample
create table MyManyIndexTable( C1 int, C2 int, C3 int, C4 int, C5 int)


create index MyManyIndexTable_I1 on MyManyIndexTable( C1)
create index MyManyIndexTable_I2 on MyManyIndexTable( C2)
create index MyManyIndexTable_I3 on MyManyIndexTable( C3)
create index MyManyIndexTable_I4 on MyManyIndexTable( C4)
create index MyManyIndexTable_I5 on MyManyIndexTable( C5)


declare @t datetime
declare @i int
Set @i = 1
set @t = getdate()
while (@i < 5000)
begin
   insert MyManyIndexTable select @i,@i,@i,@i,@i
   set @i = @i+1
end
SELECT DATEDIFF(ms, @t, getdate()) as 'Elapsed Time'

=> 3806 ms

Fixed Code Sample

Drop the index & empty the table
=> 2563 ms