How to clear the Foreign Keys field in SQL

I would like to know if there is a way to clear the user_id / store_id reference in the table

  

user_store

CREATE TABLE IF NOT EXISTS 'user'(
'id' INT(11) PRIMARY KEY AUTO_INCREMENT)

CREATE TABLE IF NOT EXISTS 'store'(
'id' INT(11) PRIMARY KEY AUTO_INCREMENT,
'name' VARCHAR(50) NOT NULL UNIQUE
)ENGINE INNODB DEFAULT CHAR SET 'utf8' AUTO_INCREMENT=10;

CREATE TABLE IF NOT EXISTS 'user_store'(
'id' INT(11) PRIMARY KEY AUTO_INCREMENT,
'user_id' INT(11) NOT NULL,
'store_id' INT(11) NOT NULL,
CONSTRAINT 'fk_user_id'
    FOREIGN KEY ('user_id')
    REFERENCES 'user'('id'),
CONSTRAINT 'fk_store_id'
    FOREIGN KEY ('store_id')
    REFERENCES 'store'('id')
)ENGINE INNODB DEFAULT CHAR SET 'utf8' AUTO_INCREMENT=10;