I have to eliminate all records with a timestamp minor or equal to 45 seconds respect to the previous…
I put in red all records that I do not want to see in my table and in green all that must remain.
I don’t understand the logic here. In 2 of the cases you show, you’re eliminating records with timestamps that are greater than 45 seconds apart from the previous row.
Assuming the timestamp is in a KNIME Date/Time format, you can use the Date&Time Difference node to calculate the difference between a Date/Time in a given row and the previous row, then use a Row Filter to remove rows in which the difference is less than some value.
as @elsamuel said first find time difference to previous row. Then I would use Rule Engine node to mark all those rows where difference is lees than 45 seconds. Newly added mark means you have to delete this and previous row judging by your example. To mark above row simulate negative lag (see here). This will give you two columns with marks. To check which rows have mark in either column and filter them I would use Rule-based Row Filter node.