Discounts are in the database in the ps_specific_price table.
DELETE FROM `ps_specific_price`; DELETE FROM `ps_specific_price_priority`; ALTER TABLE `ps_specific_price` AUTO_INCREMENT = 1; ALTER TABLE `ps_specific_price_priority` AUTO_INCREMENT = 1;
This SQL query removes all discounts and sets the index to 1.
There are other tables you need to look at.
The prefix ps_ is according to your settings.
If it's different, you have to change it.
If you have filled in columns for discounts in the CSV file, it is clear that they will not edit them. If you leave the columns in the CSV file blank, Prestashop will remove the discounts.
CSV with discount:
"ID","ACTIVE","NAME","CATEGORIES","PRICE_TAX_EXCLUDE","TAX_RULE_ID","ON_SALE","DISCOUNT_AMOUNT","DISCOUNT_PERCENT","DISCOUNT_FROM","QUANTITY","MINIMAL_QUANTITY","SHORT_DESCRIPTION","DESCRIPTION","URL_REWRITTEN"
1,1,"product one","Home",2400,1,1,10,,5,120,1,"product one","product one description","product-one"
CSV without discount:
"ID","ACTIVE","NAME","CATEGORIES","PRICE_TAX_EXCLUDE","TAX_RULE_ID","ON_SALE","DISCOUNT_AMOUNT","DISCOUNT_PERCENT","DISCOUNT_FROM","QUANTITY","MINIMAL_QUANTITY","SHORT_DESCRIPTION","DESCRIPTION","URL_REWRITTEN"
1,1,"product one","Home",2400,1,0,0,,,120,1,"product one","product one description","product-one"